Move SKU-specific events from EntitlementObserver to Handlers, cleanup useless code
Summary: Handlers are a better location for this code. Bumping entitleable->updated_at was useless.
Test Plan: ./phpunit
Reviewers: #hkccp_developers, mollekopf
Reviewed By: #hkccp_developers, mollekopf
Subscribers: #hkccp_developers
Differential Revision: https://git.kolab.org/D4607