Added is_rank to api_help and started working on ranking in streams.erl
Added user ranking. Sideeffects is that the mappings needs to be changed, a user needs a list of rankings that he/she has done and the stream user_ranking is now composed of two fields, the average rank (average) and the number of rankings (nr_rankings)
Added ranking tests
Merge branch 'develop_silver_bullet' of github.com:/projectcs13/sensor-cloud into Sp6.Sc1.user_ranking_streams

Conflicts:
	src/search.erl
	src/streams.erl
	test/search_tests.erl
	test/streams_tests.erl
	test/users_tests.erl
Changed tests according to new mapping
Merge branch 'develop_silver_bullet' of github.com:/projectcs13/sensor-cloud into Sp6.Sc1.user_ranking_streams
Changed tests according to the new mapping
Changed tests according to the new mapping
Merge pull request #156 from projectcs13/Sp6.Sc1.user_ranking_streams

Sp6.sc1.user ranking streams