Proposed fix for https://github.com/celluloid/celluloid/issues/426
If the backtrace is not an array, it crashes. https://github.com/celluloid/celluloid/issues/428
Merge pull request #429 from ioquatix/fix-backtrace-unavailable-array

If the backtrace is not an array, it crashes.
Test in ruby 2.1.2
Merge pull request #433 from cibernox/patch-1

Test in ruby 2.1.2
Merge pull request #432 from ioquatix/borked-evented_mailbox-receive

Fix broken reactor interaction with timers.
Added exclusive monotonic timeout class - consider adding directly to timers.
Handle timeout error from EventedMailbox.