Add .ruby-version and .ruby-gemset files to ignore list.
Add .ruby-version and .ruby-gemset files to ignore list.

These files are used by system to figure out which ruby version to use
when in that specific directory. The .ruby-gemset file is used by some
environmental managers.

nyc-mud-turtles-2015/nghborly,kimchanyoung/nghborly,nyc-mud-turtles-2015/nghborly,kimchanyoung/nghborly,kimchanyoung/nghborly,nyc-mud-turtles-2015/nghborly