title: babel does not inject relative requires into the output
body: <p>I run babel against my source files, i want to output one single file, with all the relative imports injected inside the file.</p>
  
  <h1>Source structure</h1>
  
  <pre><code>src
  │   index.js
  │   relative-file.js    
  │
  └───some-folder
          another-relative-file.js
  </code></pre>
  
  <p>the index file requires <code>relative-file</code>, and the <code>relative-file</code> requires <code>another-relative-file</code>.</p>
  
  <h1>Expected output</h1>
  
  <p><code>index.js</code> with no relative requires, everything is injected inside this one file.</p>
  
  <h1>Actual output</h1>
  
  <p><code>index.js</code> with <code>require('./relative-file')</code> inside.</p>
  
  <h1>Tried babel-cli commands</h1>
  
  <pre><code>babel src --out-file distribution/index.js
  </code></pre>
  
  <p>output a dir will put output multiple files requiring each other just like the source.</p>
  
  <pre><code>babel src --out-dir distribution
  </code></pre>