Moving REST client classes to separate module

Removing classes, replacing with SBT dependency
Changing package prefix of REST client classes
Merge branch 'master' of github.com:Graylog2/graylog2-web-interface

Conflicts:
	app/models/Extractor.java
	app/models/UniversalSearch.java
	app/views/search/results.scala.html
Merging missing commits:

ceaca33604026fc52d1c87aa02229449f5d89f76
48f598cc37523cd9a6fb629e54cd95703e4ad0c8
a807ffba1cc8c408156d059ce4ee1e8f084e2726