Karma BrowserStack reporting enhancements

[samirans89]

Current reporting ability of the Karma Launcher is only to mark status = 'failed' for a session. Does not handle success, timeouts, disconnect cases. Also, there is no provision added to mark failure reasons. 
This PR implements the following changes:

• Handle additional Karma events for ‘spec complete’, ‘spec success’, ‘spec failure’, ‘spec skipped’, ‘browser complete’, ‘browser error’, ‘run complete’ for session reporting requirements 
• Update ‘Session Name’ with Karma ‘Test Suite name’ which got executed in the sessionUpdate session ‘Status’ field to ‘Passed’ or ‘Failed’ based on the actual session run
• Update the session ‘Reason’ field (255 chars) with the ‘specs completed’ within the session for ‘Passed’ runs and the first failure reason for ‘Failed’ runs
• Update ‘Build Name’ post batch execution of Karma tests with the number of specs passed, failed (if any) and also report whether the session encountered any disconnects / browser errors.

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