Update dependencies. Fixes Sass error

Gemfile

@@ -2,15 +2,15 @@ source 'https://rubygems.org'
 
 
 # Bundle edge Rails instead: gem 'rails', github: 'rails/rails'
-gem 'rails', '4.1.7'
+gem 'rails'
 # Use sqlite3 as the database for Active Record
 gem 'sqlite3'
 # Use SCSS for stylesheets
-gem 'sass-rails', '~> 4.0.3'
+gem 'sass-rails'
 # Use Uglifier as compressor for JavaScript assets
-gem 'uglifier', '>= 1.3.0'
+gem 'uglifier'
 # Use CoffeeScript for .js.coffee assets and views
-gem 'coffee-rails', '~> 4.0.0'
+gem 'coffee-rails'
 # See https://github.com/sstephenson/execjs#readme for more supported runtimes
 # gem 'therubyracer',  platforms: :ruby
 gem 'slim-rails'