Updating the doc to Ruby 2.0

Was experimenting with using ERB and Jekyll (massive fail) but part of that
project that was useful was updating doc to Ruby 2.0.

Jekyll has also been updated to v1.2

All seems to be working right now except `foreman`, which puts out weird errors
on Interrupt under Ruby 2.0. Seems like they are aware of problem and working
to fix it.

Since foreman is not used in production, I feel like this is ready for the big
time. Not sure how it will affect the docbox, however. 

@freerobby would you have any insight on this? Also, should I switch from `.rvmrc` to `.ruby-version` as requested?