remove the lock when when it exists, but it's out of date
use the method
use new ttl method
add guards to this check
update gemfile source to silence warning
write spec, fix bugs

using #to_i changes the truthiness of the value returned from get_lock
Merge branch 'double_check_key_expiration' of git://github.com/dougcole/resque-uniq into dougcole-double_check_key_expiration

Conflicts:
	Gemfile