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.

With this commit the icons from FontAwesome are used. To achive this the
webpack css-loader is used and the location for the module.css has slightly
changed.
Also I removed the ugly sidebar (what a short life) and added a slim navbar at
the top for the detail views.

 - Updated Angular to 1.5.3
 - Removed Angular UI Bootstrap, to make the Angular update possible without
   updating Bootstrap
 - Moved every view into its own module
 - Added concatenation of the module js and css assets to the webserver
 - Created directives/components for the various visual components and trimmed
   down the controllers
 - Removed unecessary ngRoute
 - Removed classpath section in details (it is included in environment)
 - Moved the counters and gauges to a separated metrics view
 - Added target="_blank" for the logfile
 - Added information about version, loaded ui modules to the about page
 - Extracted the activiti view to a separate maven artifact

With this commit it is now possible to add your own ui modules to the servers
classpath and they will show up in the ui.
Every module needs an "entry" script file in the classpath located under
`META-INF/spring-boot-admin-server-ui/<modulename>/module.js`.
The module is be implemented as angular module and needs to be added to
the global `uiModules` list.
The spring-boot-admin-server-ui-activiti module is a simple sample for
adding a application view but it is also possible to add main-views.
Please have a look at the events module in spring-boot-admin-server-ui/modules.

Please note that the internals of the ui can change anytime.

fixes #107

using Gulp & Browserify
with a little help from https://blog.codecentric.de/en/2014/08/angularjs-browserify

* Separate AppStore from AppRegistry
* Allow Id generation to be altered
* Remove logic from Application; Move id genretation into AppRegistry
* Make AppStore threadSafe