Until now the thread querying the application endpoint can be blocked
for a very long time when the application is inresponsive. With this
commit two new properties `spring.boot.admin.monitor.read-timeout`
(default: 2s) and `spring.boot.admin.monitor.connect-timeout` (default:
5s) are added.

closes #462

A new property `spring.boot.admin.discovery.services` is added. It can
be used to restrict the services registered via discovery to a
whitelist (supporting simple patterns). Until now only blacklistin was
supported. The default whitelist permits all services.

https://github.com/spring-cloud/spring-cloud-netflix/pull/1372 has been
merged. So it is save to remove the local workaround.

Adds an new Notifier implementation for Let's Chat.

Since the Notifiers shouldn't throw exceptions, we let all extend the
AbstractEventNotifier which gets us a enabled property and catching
exceptions which may occur when notifiying.

To make custom NotifierConfigurations easier and less error prone we now
instantiate the Notifier Beans regardless of the corresponding enabled
property

closes #402

Posting via zuul doesnt work in case the Content-Type has a charset
specified.
Applied fix from spring-cloud/spring-cloud-netflix#1663

fixes #403

For easier cusotmization. E.g. converting some of the data fechted
from the /info endpoint or to filter it.

Apparently we need some getters so that the metadata for the
configuration properties is generated.

fixes #391

closes #386

My PR spring-cloud/spring-cloud-netflix#1448 has been merged into
Dalston, therefore we can remove our implementation and need to fix some
comile issues.

fixes #382

With this commit you can use simple patterns to match services to
ignore.
A pattern can look like this "foo*", "*foo", "foo*bar".

closes #377

The info is now fetched by the server on status change. This way the
info can be used in the notifications and also improves performance when
listing a huge amount of applications in the ui.

closes #349

With this change it is possible to include credentials in the instance
metadata which will then be used to access the client endpoints using
HTTP Basic authorization.

closes #359

With this commit you can now associate your applications with custom
metadata using `spring.boot.admin.client.metadata.*` sensitive values
are recognized by key and are masked in the http interface.

This can be useful in the future if there are instance specific settings
which should be used by the admin server, e.g. custom notification
recipients.

For now there is no extra imetadata view in the ui. The values are shown
in the environment view.

From this commit on the source from wich the application was registered
is remembered. We use this information for two things:
 * For applications which wasn't registered via the http-api the remove
   button is hidden.
 * The `ApplicationDiscoveryListener` only removes stale applications
   (those which are not anymore found via discovery) if the were registered
   via the `ApplicationDiscoeryListener`.

closes #328

The StatusInfo has a new details field. The StatusUpdater puts either the
reponse from the health endpoint or the exception message in the details.
This allows us to see the details over time (via the journal) and also to
use `em in a bit more mail notifications.

closes #329

With this commits the server no longer depends on the client. The
classes for the clients are moved to de.codecentric.boot.admin.client
package.
Since the perspective on applications is totally different from client
and server the model has been split apart.

What means this for users:
1) The client is no longer a transitive dependency for your admin server
you may need to add it explicitly to your dependencies, respectively
jolokia-core in case you're using discovery and want to use the jmx-bean
interface

2)In case you have cutomised parts of the client you need to reflect the
package change.

fixes #332

Add support for the /loggers endpoint from spring boot 1.5.x. With this
change log4j2 (and every other logging backend supported by spring boot)
is supported in the logging view.
The old implementation will be kept a while, so that the clients aren't
forced to migrate.

closes #305

fixes #317

closes #321

Annotating the applicationRouteLocator bean with
@ConfigurationProperties yields the wrong configuration metadata.
Instead do a explicit properties bean to get correct metadata.

fixes #309

This CompositeRouteLocator allows extensions to add custom RouteLocators

To easily add new mvc controllers (e.g. from extensions) a new
annotation `@AdminController` is added.

 * Since the hystrix.stream incorrectly handles HEAD requests we had to change
   the detection for the hystrix-endpoint to a GET request.
   Issue https://github.com/Netflix/Hystrix/issues/1369

 * We need to improve Zuul's SimpleHostRoutingFilter and SendResponseFilter to
   close the underlying socket when an error occurs when writing the response.
   I hope that the code can be removen when my PR gets merged.
   Issue https://github.com/spring-cloud/spring-cloud-netflix/pull/1372

Fixes #290

With the fix for #260 we ignored all events from child contexts which turns out
to be wrong since the "main" application context is, in case spring cloud config
is used, is a child  of the bootstrap context. So we just act on the events from
WebApplicationContexts. After they're fired up the needed port information is
available.

fixes #277