title: react_on_rails install: yarn is required error
body: <p>I am trying to setup react_on_rails for an existing rails 5.0 app as per the following instructions:
  <a href="https://github.com/shakacode/react_on_rails" rel="noreferrer">https://github.com/shakacode/react_on_rails</a></p>
  
  <ol>
  <li>gem "react_on_rails", "8.0.0"</li>
  <li>rails generate react_on_rails:install</li>
  </ol>
  
  <p>I get the following error:</p>
  
  <pre><code>ERROR: yarn is required. Please install it before continuing. https://yarnpkg.com/en/docs/install
  </code></pre>
  
  <p>now this is my yarn, npm and node path:</p>
  
  <pre><code>[user@server]$ which node
  /usr/bin/node
  [user@server]$ which npm
  /usr/bin/npm
  [user@server]$ which yarn
  ~/.yarn/bin/yarn
  </code></pre>
  
  <p>How do i ensure it's using the appropriate yarn and help install react_on_rails?</p>
  
  <p>EDIT: This is my ~/.bashrc file:</p>
  
  <pre><code>export PATH="$HOME/.rbenv/bin:$PATH"
  eval "$(rbenv init -)"
  
  
  export NVM_DIR="$HOME/.nvm"
  [ -s "$NVM_DIR/nvm.sh" ] &amp;&amp; \. "$NVM_DIR/nvm.sh"  # This loads nvm
  [ -s "$NVM_DIR/bash_completion" ] &amp;&amp; \. "$NVM_DIR/bash_completion"  # This loads nvm bash_completion
  
  export PATH="$PATH:$HOME/.yarn/bin"
  </code></pre>
  
  <p>This is my /bin/yarn file under my app:</p>
  
  <pre><code>#!/usr/bin/env ruby
  VENDOR_PATH = File.expand_path('..', __dir__)
  Dir.chdir(VENDOR_PATH) do
    begin
      exec "yarnpkg #{ARGV.join(" ")}"
    rescue Errno::ENOENT
      $stderr.puts "Yarn executable was not detected in the system."
      $stderr.puts "Download Yarn at https://yarnpkg.com/en/docs/install"
      exit 1
    end
  end
  </code></pre>