Stop by CTRL+C in "Embedding Sinatra within EventMachine" sample

The present sample does not stop when CTRL+C is pressed because the signal
is processed by thin server. Set "signals" option to false to avoid this.
Merge pull request #95 from nota-ja/pr-enable-to-stop-by-ctrl-c

Stop by CTRL+C in "Embedding Sinatra within EventMachine" sample