title: Gemfile ROR version and local machine ROR version mismatch
body: <p>I am a complete beginner to ROR and heroku. Currently I am trying to create an app with a git from bitbucket and my gemfile version (2.2.3) is different from my ruby on rails version of 2.3.1.</p>
  
  <p>What are the steps I can take to ensure that my gemfile can be changed?</p>
  
  <p>This mismatch in gemfile caused my "git push heroku master" to fail with the following errors.</p>
  
  <p><strong>An error occurred while installing mime-types (3.0), and Bundler cannot
  remote:continue.</strong></p>
  
  <p>Thank you so much! (:</p>