Conditions for the new diff function for vstreams
Merge branch 'develop' of github.com:projectcs13/sensor-cloud into Sp8.Sc2.DiffVstream
Merge pull request #227 from projectcs13/Sp8.Sc2.DiffVstream

Sp8.sc2.diff vstream
Merge branch 'develop' of github.com:projectcs13/sensor-cloud into sp8.sc3.virtual-stream-process-termination
Vitual streams have function diff, work only when subscribing to one stream, and test case to try it