Support numbers in json.

Moin Thorsten,

I hope all is good in HH :)?!

I'm using your great gem to test my JSON responses. Today I noticed that using regexes together with plain numbers (vs. quoted ones "1") is not working (tested on 2.1.2p95). It throws a TypeError:

`TypeError: no implicit conversion of Fixnum into String`

I have fixed that issue and added a test for it.

Cheers,
plu