Added Monkey Language

Language is new in pygments 1.6.

I checked, it also already is in [pygments.rb/lexers/compiled.py](https://github.com/tmm1/pygments.rb/blob/master/vendor/pygments-main/pygments/lexers/compiled.py#L3061)

After doing `rake samples` and `rake test`, the diff for _samples.json_ was huge, i did not dare include it in this PR. If somebody tells me that it's ok, I will add it :)