Replace hpricot by nokogiri
Update .ruby-version
Update .ruby-version
Unignore .ruby-version
Merge PR#3541 to this branch to undo it.
Unincluding hpricot

The Gemfile was badly formatted anyway, since it lacked a justifying
comment, as all other included gems have.
Merging my fix to #3537, nokogiri for msfcrawler
Land #3537 from @PagedeGeek, msfcrawler fix