Convert from .rvmrc to .ruby-version

Recommended by latest version of RVM.
Source gems from https://rubygems.org

Avoids gem warning.
Bump Rails 3.2.x to latest 3.2.13
Updates for Rails 3.2.13

Using rake rails:update after updating Gemfile and re-bundling.
Schema updated by Rails 3.2.13
Make model attributes accessible
Updated Ruby to ruby-1.9.3-p392