changed HipchatNotifierConfiguration to be a static class, otherwise application context doesn't start up when hipchat notification is enabled.

The RemindingNotifier sends periodic notifications using a delegate. It must be
added explicitly to the ApplicationContext

The polling in the UI is replaced with server side events. Status changes are
now reported immediately from the admin server to the UI.

Cause it was often requested, now the context-path for the admin server is
configurable. This allows to move the admin-ui and endpoints to other http-
paths than "/".
NOTE: I'd still advise not to add the admin to the application you want to
monitor.

Spring Cloud Brixton hasn't been released yet, so to get the Spring Boot Admin
release out. We downgrade to Spring Cloud Angel.SR3.

To not pollute the log with warnings when an app is offline log the exception with
debug when the application status already was offline before the check. So only the
first exception when the state changes to offline will be logged.

closes #125

To not accidentally expose senstive urls only expose whitelisted
management-endpoints via the zuul proxy filter.

Deriving from Spring Clouds ProxyRouteLocator has become too difficult. It would
have required to either set fixed ZuulProperties or providing a DiscoveryClient.
So we are shipping our own lean version of it. Since the PreDecorationFilter is tightly
coupled to the ProxyRouteLocator we also have to use our own stripped down version.

closes #123

Check if the status field is a String and don't propagate any Exception
from the StatusUpdater, so that the application don't fail like in #120

Streamline the Hazelcast support with boot 1.3 and support storing events in hazelcast

closes #113

Due to our use of @Conditionals on our @Configuration-classes the import must be deferred, so that the classes are processed after all other @Configuration-classes

remove logfileEndpoint
rename logback.xml to logback-spring.xml in samples

fixes #98

 * Use @EventListener instead of ApplicationListener-interface
 * Don't inherit ClientApplicationEvent from ApplicationEvent - so JournaledEvent isn't needed anymore
 * added eclipse formatter rules
 * reformatted all files

Remove unecessary dependencies

fixes #105

The mail notification is enabled if a mailSender is present specified via spring.mail.* properties.
On default the mail is sent to root@localhost and the chages from UNKNOWN to UP are ignored.

Added a simple event journal, jorunaling all ClientApplicationEvents using a simple, non-persistent store. So all information is lost after restart. Added corresponding view to UI.

The health-check is made at a fixed interval (default: 10s) for all expired status-information (default-lifetime: 30s).
The application health-endpoint must either respond with a JSON-Body having a status-field or with an empty body and all 2xx-http-responses are interpreted as UP and every other status as DOWN.

fixes #61

To enable, you just have to add a DiscoveryClient to your Spring Boot Admin Server.
Also did some code polish.
Closes #44