fix/hack signal handling and condition variables and mutex with Ruby 2.0...

Hello,

This is a hacky and naive solution regarding #4 .

I'm replacing with a simple poll loop (with `sleep 1`) all functionality of the condition variable which makes the signal queue like act like a blocking queue. So my solution is much less elegant.

Please feel free to consider it if it is suitable.

Other libraries are having similar problems, see
https://github.com/celluloid/celluloid/issues/121

Thanks :+1: