Specified proper Ruby version

Signed-off-by: Evan Tedesco <e.tedesco@{"me"="twenty4play@gmail.com", "et"="evantedesco@gmail.com"}>
added Heroku URL to readme, changed Gemfile to not install dev tools on Heroku

Signed-off-by: Evan Tedesco <e.tedesco@{"me"="twenty4play@gmail.com", "et"="evantedesco@gmail.com"}>