[minor] adding strict mode
[minor] Abstract adapter in its own primus-rooms-adapter module
[minor] replacing adapter.add with adapter.set
[doc] adding some primus-rooms-adapter documentation
[release] 3.0.2
[fix] fixing breaking change #39
[release] 3.0.3
[fix] Save a reference to the Primus instance

The reference to the Primus instance in the `spark` is removed when the connection is closed.
It is possible that we try to access the property when it has already been deleted.

To avoid this we save a reference to the Primus instance in the Rooms instance.
[release] 3.0.4
[doc] Adding optional callback on `spark.leaveAll`
Merge pull request #42 from Nicolab/master

[doc] Adding optional callback on `spark.leaveAll`
[doc] Use SVG badges
[test] Cleaning up a test and removing trailing spaces
[minor] Removing trailing spaces
[doc] Fixing documentation for the `isRoomEmpty` method