title: Rubocop using wrong version of Ruby - Fails
body: <p>I've re-installed RVM, Ruby and all gems using rvm implode. When I run rubocop, I receive an error that it is using 2.5 (which I did not explicitly install but seems to come with RVM's Ruby 2.5.1)</p>
  
  <p>Note the line I have highlighted with * * - this may be the issue?</p>
  
  <pre><code>$ which ruby
  /Users/Will/.rvm/rubies/ruby-2.5.1/bin/ruby
  $ rvm use 2.5.1
  Using /Users/Will/.rvm/gems/ruby-2.5.1
  $ rubocop
  Inspecting 604 files
  
  
  0 files inspected, no offenses detected
  Unknown Ruby version: 2.5
  /Users/Will/.rvm/gems/ruby-2.5.1/gems/rubocop-0.49.1/lib/rubocop/processed_source.rb:131:in `parser_class’
  /Users/Will/.rvm/gems/ruby-2.5.1/gems/rubocop-0.49.1/lib/rubocop/processed_source.rb:138:in `create_parser’
  /Users/Will/.rvm/gems/ruby-2.5.1/gems/rubocop-0.49.1/lib/rubocop/processed_source.rb:94:in `parse’
  /Users/Will/.rvm/gems/ruby-2.5.1/gems/rubocop-0.49.1/lib/rubocop/processed_source.rb:36:in `initialize’
  /Users/Will/.rvm/gems/ruby-2.5.1/gems/rubocop-0.49.1/lib/rubocop/processed_source.rb:17:in `new’
  /Users/Will/.rvm/gems/ruby-2.5.1/gems/rubocop-0.49.1/lib/rubocop/processed_source.rb:17:in `from_file’
  /Users/Will/.rvm/gems/ruby-2.5.1/gems/rubocop-0.49.1/lib/rubocop/runner.rb:334:in `get_processed_source’
  /Users/Will/.rvm/gems/ruby-2.5.1/gems/rubocop-0.49.1/lib/rubocop/runner.rb:110:in `block in file_offenses’
  /Users/Will/.rvm/gems/ruby-2.5.1/gems/rubocop-0.49.1/lib/rubocop/runner.rb:121:in `file_offense_cache’
  /Users/Will/.rvm/gems/ruby-2.5.1/gems/rubocop-0.49.1/lib/rubocop/runner.rb:109:in `file_offenses’
  /Users/Will/.rvm/gems/ruby-2.5.1/gems/rubocop-0.49.1/lib/rubocop/runner.rb:100:in `process_file’
  /Users/Will/.rvm/gems/ruby-2.5.1/gems/rubocop-0.49.1/lib/rubocop/runner.rb:78:in `block in each_inspected_file’
  /Users/Will/.rvm/gems/ruby-2.5.1/gems/rubocop-0.49.1/lib/rubocop/runner.rb:75:in `each’
  /Users/Will/.rvm/gems/ruby-2.5.1/gems/rubocop-0.49.1/lib/rubocop/runner.rb:75:in `reduce’
  /Users/Will/.rvm/gems/ruby-2.5.1/gems/rubocop-0.49.1/lib/rubocop/runner.rb:75:in `each_inspected_file’
  /Users/Will/.rvm/gems/ruby-2.5.1/gems/rubocop-0.49.1/lib/rubocop/runner.rb:67:in `inspect_files’
  /Users/Will/.rvm/gems/ruby-2.5.1/gems/rubocop-0.49.1/lib/rubocop/runner.rb:39:in `run’
  /Users/Will/.rvm/gems/ruby-2.5.1/gems/rubocop-0.49.1/lib/rubocop/cli.rb:82:in `execute_runner’
  /Users/Will/.rvm/gems/ruby-2.5.1/gems/rubocop-0.49.1/lib/rubocop/cli.rb:28:in `run’
  /Users/Will/.rvm/gems/ruby-2.5.1/gems/rubocop-0.49.1/bin/rubocop:13:in `block in &lt;top (required)&gt;'
  */Users/Will/.rvm/rubies/ruby-2.5.1/lib/ruby/2.5.0/benchmark.rb:308:in `realtime’*
  /Users/Will/.rvm/gems/ruby-2.5.1/gems/rubocop-0.49.1/bin/rubocop:12:in `&lt;top (required)&gt;'
  /Users/Will/.rvm/gems/ruby-2.5.1/bin/rubocop:23:in `load’
  /Users/Will/.rvm/gems/ruby-2.5.1/bin/rubocop:23:in `&lt;main&gt;'
  /Users/Will/.rvm/gems/ruby-2.5.1/bin/ruby_executable_hooks:24:in `eval’
  /Users/Will/.rvm/gems/ruby-2.5.1/bin/ruby_executable_hooks:24:in `&lt;main&gt;'
  </code></pre>