Changes in grunt, to be more regexpy
Changes in grunt, to be more regexpy

I have tried to use regexp as much as I could for this impl. The
implemenation is not so fast as one could imagine, but is not so bad
either (better than the trial division version, aka, primo.pl).
In my macbook pro, i7, takes 232172.000 msec.

darkturo/primo,darkturo/primo,darkturo/primo