Merge pull request #195 from swistak/master

Move trapping of SIGINT to load time.
Release 2.6.2
Merge pull request #196 from swistak/master

Remove no longer valid spec that checks trapping of SIGINT
Preventing finalization on dead actor

When using Calluloid.shutdown there's race condition between listeners
and celluloid which in some cases leads to Listener calling #finalize on
dead actor. Added a guard that checks if actor is alive when we're
exiting from #_wait_for_changes and calls finalizer only if it's alive.

PS. I couldn't for a life figure out how to make this test pass. I hate
mocking libraries with all my heart. Feel free to fix this.

Fixes #197