closes #439

Adds a workaround for
https://github.com/spring-cloud/spring-cloud-netflix/issues/1815
by including spring-cloud-context to the server's dependencies

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.

Brings a fixed httpclient.

fixes #419

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.

The value from max memory isn't necessarily the -Xmx parameter,
therefore we remove the label

fixes #413

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

closes #404

When the jolokia endpoint is missing the jmx section is hidden
additionally when the logging endpoint is also missing the logging
section is hidden too.

closes #398

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

For smaller screens (< 992px) the info is hidden from the application
list. Also the Status and the actions buttons are now shown on two
lines, so that longer statuses don't overlap with the buttons.

fixes #394

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

fixes #391

fixes #395

fixes #387

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

Wooohoo!