Update Gemfile, add production/development/test groups

Gemfile

@@ -5,9 +5,6 @@ gem 'rails', '3.2.11'
 # Bundle edge Rails instead:
 # gem 'rails', :git => 'git://github.com/rails/rails.git'
 
-gem 'sqlite3'
-gem 'mysql2'
-
 # Gems used only for assets and not required
 # in production environments by default.
 group :assets do
@@ -15,7 +12,7 @@ group :assets do
 #  gem 'coffee-rails', '~> 3.2.1'
 
   # See https://github.com/sstephenson/execjs#readme for more supported runtimes
-  # gem 'therubyracer', :platforms => :ruby
+  gem 'therubyracer', :platforms => :ruby
 
   gem 'uglifier', '>= 1.2.2'
 end
@@ -37,15 +34,15 @@ gem 'acts_as_commentable_with_threading'
 gem 'prawn'
 gem 'prawn_rails'
 gem 'gravtastic'
-
-# To use Jbuilder templates for JSON
-# gem 'jbuilder'
-
-# Use unicorn as the app server
-# gem 'unicorn'
-
-# Deploy with Capistrano
-# gem 'capistrano'
-
-# To use debugger
-# gem 'debugger'
+group :development, :test do
+  gem 'pry'
+  gem 'sqlite3'
+  gem 'thin'
+  gem 'rspec-rails', '2.11.0'
+end
+group :production do
+  gem 'mysql2'
+end
+group :test do
+  gem 'capybara', '1.1.2'
+end