Atmosphere Update to 2.0.7

This update will hopefully fix the problem with the "This message Entry{message=Weather_Chart_Period (Type=NumberItem, State=0), type=ALL, future=org.atmosphere.cpr.BroadcasterFuture@bec2338} will be lost" error (see #765 ).

The first try (PR #1100) which updated atmosphere to 2.1.5 leads to a lot of code changes since the API seems to change in 2.1.x. Changelog of 2.0.5 talks about fixing errors that sounds a lot like same issue we have to solve.