Count platform by unique machines; add support for specifying start and
end dates
Merge branch 'master' into count_sources_by_unique_machine

Conflicts:
	stats/views.py
Fix merge error.
Fix wrong JSON property name in results for detailed sources
Merge pull request #27 from dfedorth/count_sources_by_unique_machine

Count platform by unique machines; add support for specifying start and end dates