title: Error when running `feathers generate authentication` for `RethinkDB`
body: <p>I’m having issues when running <code>feathers generate authentication</code> with selecting <code>rethinkdb</code> as database.</p>
  
  <p><em>Environment:</em></p>
  
  <ul>
  <li>Mac OS X Sierra </li>
  <li>feathers 2.2.3 </li>
  <li>npm 5.1.0 </li>
  <li>rethinkdb 2.3.5</li>
  </ul>
  
  <p><em>Steps to reproduce:</em></p>
  
  <ol>
  <li>I have up and running <a href="https://github.com/tenzan/feathers-chat.git" rel="nofollow noreferrer">https://github.com/tenzan/feathers-chat.git</a></li>
  <li><code>feathers generate authentication</code></li>
  <li>Select <code>Username + Password (Local)</code></li>
  <li>What is the name of the user (entity) service? (users) &lt;-- Enter</li>
  <li>What kind of service is it? (Use arrow keys) ❯ RethinkDB &lt;-- Enter</li>
  </ol>
  
  <p><em>Output:</em></p>
  
  <pre><code>events.js:182
        throw er; // Unhandled 'error' event
        ^
  
  TypeError: Parameter "url" must be a string, not object
      at Url.parse (url.js:102:11)
      at Object.urlParse [as parse] (url.js:96:5)
      at ConnectionGenerator._getConfiguration (/usr/local/lib/node_modules/feathers-cli/node_modules/generator-feathers/generators/connection/index.js:46:24)
      at ConnectionGenerator._writeConfiguration (/usr/local/lib/node_modules/feathers-cli/node_modules/generator-feathers/generators/connection/index.js:103:32)
      at ConnectionGenerator.writing (/usr/local/lib/node_modules/feathers-cli/node_modules/generator-feathers/generators/connection/index.js:297:10)
      at Object.&lt;anonymous&gt; (/usr/local/lib/node_modules/feathers-cli/node_modules/yeoman-generator/lib/index.js:417:23)
      at /usr/local/lib/node_modules/feathers-cli/node_modules/run-async/index.js:25:25
      at Promise (&lt;anonymous&gt;)
      at /usr/local/lib/node_modules/feathers-cli/node_modules/run-async/index.js:24:19
      at /usr/local/lib/node_modules/feathers-cli/node_modules/yeoman-generator/lib/index.js:418:9
  </code></pre>
  
  <p>I had same errors on different Mac PCs with same environment.</p>