updated readme - install instructions - imagemagick installation
Updated Ruby to 2.1.2

It was necessary to uninstall pry-debugger in favor of pry-byebug,

because the debugger gem doesn't offer full support to Rails 2

References:

http://stackoverflow.com/questions/20826568/debugger-gem-not-supported-in-ruby-2-1-0-2-1-1-2-1-2

https://github.com/cldwalker/debugger/issues/125#issuecomment-43353446