When the list contains a lots of applications many requests are made for
dynamic views (e.g. heapdump, flyway, logfile, ...). With this commit
the availability check for these views is deferred until the user opens
toggles the dropdown. This should lead to far fewer requests.

fixes #346

Additionally the url list is not anymore overlapped then having a lot of
tabs for the detail views.

fixes #347

closes #237

Using an absolut url in $http.get doesn't work when the server.context-path has
been changed for the admin server. Like in all other places a relative url has
to be used.

fixes #256

Adds an application view that displays a list of
Liquibase migrations as retrieved from the /liquibase Actuator
endpoint. The module is conditional on this endpoint being
available.