title: How do I switch my Ruby version for a single project only?
body: <p>I was reading that rbenv can be used to switch the Ruby environment for a single project only.  I have Ruby 2.4 installed on my system, but I'd like to use version 2.3 for a specific project only.  I thought using "rbenv local" would heal the pain but it does not ...</p>
  
  <pre><code>localhost:myproject davea$ rbenv local 2.3.0
  localhost:myproject davea$ bundle install
  Your Ruby version is 2.4.0, but your Gemfile specified 2.3.0
  localhost:myproject davea$ ruby -v
  ruby 2.4.0p0 (2016-12-24 revision 57164) [x86_64-darwin16]
  </code></pre>
  
  <p>How do I use Ruby 2.3 for this project only?  </p>