Upgraded Rails from 3.2.11 to 3.2.19 - Step 1 of Rails 4.1.x upgrade + Gemfile.lock updates

Step 1 of Rails 4.1.x upgrade (suggested by Ken in #140)
  * Upgraded **rails** gem from 3.2.11 to 3.2.19 (latest Rails version) and removed explicit **rack** gem line.