bringing back the fp-growth code in mahout

[ray]

I had it in mind to volunteer to maintain the fp-growth code in Mahout, 
but I see that Spark has an fp-growth implementation.  So now that I 
have the time to work on this, I'm wondering if there is any point, or 
if there is still any interest in the Mahout community.

If not, so be it.  If so, I volunteer.
Regards, Ray.