Adds the .ruby-version file to the .gitignore
Adds the .ruby-version file to the .gitignore

This will prevents problems with people that uses rbenv with Boxen and people that installs rbenv only.

jinutm/silveralms.com,gustavoguichard/neighborly,gustavoguichard/neighborly,raksonibs/raimcrowd,jinutm/silveralms.com,jinutm/silverpro,jinutm/silverpro,raksonibs/raimcrowd,jinutm/silverprod,raksonibs/raimcrowd,jinutm/silverme,MicroPasts/micropasts-crowdfunding,jinutm/silverprod,raksonibs/raimcrowd,jinutm/silveralms.com,MicroPasts/micropasts-crowdfunding,MicroPasts/micropasts-crowdfunding,MicroPasts/micropasts-crowdfunding,gustavoguichard/neighborly,jinutm/silverme,jinutm/silverme,jinutm/silverprod,jinutm/silverpro