Get rid of twitter-bootstrap-rails gem, update others accordingly.

Gemfile

@@ -1,6 +1,7 @@
 source 'https://rubygems.org'
 
 gem 'rails', '3.2.13'
+gem 'rake', '< 11.0'
 
 gem 'netzke-cancan'
 gem 'netzke-core', '~>0.8.0'
@@ -12,7 +13,7 @@ gem 'bootstrap-will_paginate', '~> 0.0.6'
 gem 'cancan'
 gem 'decent_exposure', '~> 1.0.1'
 gem 'devise', '~> 2.0.4'
-gem 'haml-rails', '~> 0.3.4'
+gem 'haml-rails'
 gem 'jquery-rails', '~> 2.0'
 gem 'pg', '~> 0.17.1'
 gem 'will_paginate', '~> 3.0.3'
@@ -21,8 +22,9 @@ gem 'jbuilder', '~> 2.0.3'
 # Gems used only for assets and not required
 # in production environments by default.
 group :assets do
+  gem 'sass-rails', '~> 3.0'
   gem 'coffee-rails', '~> 3.2.1'
-  gem "twitter-bootstrap-rails", "~> 2.0.3"
+  gem 'bootstrap-sass', '~> 3.1.1'
 
   # See https://github.com/sstephenson/execjs#readme for more supported runtimes
   # gem 'therubyracer'