add .travis.yml
Revert "Remove safe_shutdown task, it's no longer helpful."

This reverts commit 3fba11aaee54d029bb63ecc854c662b1ced584a7.
Revert "Use a monitor to protect worker pool configuration methods."

We need to be able to set Que.mode = :off when trapping INT and TERM signal, so in order to work with Ruby 2.0+ it can't lock a mutex.

This reverts commit ec480d0cc7a97d81c4c8d047ecee148bf8201d16.

Conflicts:
	CHANGELOG.md
Have workers safely finish all jobs before exiting.
Update changelog with new shutdown behavior.
Add a spec for specifying log levels.
Merge branch 'travis' of https://github.com/joevandyk/que
Add a few more Ruby versions to Travis.