remove hpricot dependency

[i5okie]

Would it be a lot of work to replace hpricot dependency with Nokogiri instead?

[fmorales]

This is something we have been thinking about, since hpricot is so old.

[i5okie]

It would make Reve usable with Rails 4 a bit easier

[lisa]

This is on my radar. I'm just poking at Nokogiri now.

[lisa]

@i5okie @fmorales

If either of you are still looking for this feature please refer to #17 and test that PR by testing the branch locally.