FC-38 System events and handlers for blue-green deployment

Handlers for new system events have been added, but they do not have any action yet.
Also corrected an issue where rate limiter was applied for ignored messages.

Signed-off-by: Steffan Westcott <steffan.westcott@clicktravel.com>
Merge pull request #2 from clicktravel-steffan/master

FC-38 System events and handlers for blue-green deployment