Adding Factory to Stream class utilizing Assisted Injection

Using this, we are able to inject UserService class which allows us to
return a User object in getCreatorUser.
Enhancing Streams index page

Replacing POST->Redirect cycle for Stream deletion by JS-button.
Adding link to creatorUser for each stream.
Changing type of streams from API response object to proper Stream.
objects.
Improving stream message browsing

Refactoring SearchController by extracting stream search to separate
inherited controller.
Searching for streams using filter instead of query parameter.
Fixing pagination by replacing call to UniversalSearch object which
generates static call object with helper that modifies current call.
Adding pausing/resuming to stream index page.
Merge git://github.com/Graylog2/graylog2-web-interface into develop