Fixing Stream pausing

When a stream is paused, it would not appear in the list of streams
returned by the StreamResource. The method was split up into two
methods, one returning all streams, the other returning all enabled
streams (which is also used by the stream router).
Fixing compilation error related to new Version class
Adding filter to AbsoluteSearch

The optional filter parameter of an AbsoluteSearch request is now
considered for message index retrieval.
Adding filter to KeywordSearch
moved inputs to own maven submodule
maven structure of stand-alone graylog2-radio
work on radio
radio now registering in server cluster
REST APIs for radio
fix licenses of package moved files