Added concurrency protection to broker (original file by Jorge)
Changed broker to follow syncronization lock conventions.
Updated GitHubBroker. Callback instance now has to be provided for all callback methods. Disconnect is not a callback method anymore. Tests and related files have been updated.
Added tests for null callbacks.
Fixed index-out-of-bounds bug in GitHubBroker.
Removed unused callback method from GitHubBrokerListener.
Fixed index-out-of-bounds bug in GitHubBroker.
Removed unused callback method from GitHubBrokerListener.
Pull-merge with branch