Merge pull request #4 from katreniak/bka-signalContext

Add optional context parameter to bind() calls
Update README.md

Rewrite the section on automatic disconnection when the receiver associated with a callback is destroyed to reference the new 'context' parameter to QtSignalForwarder::connect()
testContextDestroyed: check that the qt connection is really disconnected

Signed-off-by: Branislav Katreniak <bkatreniak@nuvotechnologies.com>