title: Installation of Magento 2 error: php ext-gd is required
body: <p>I am trying to install <code>magento/product-community-edition 2.1.3</code> in <code>cloud9 (Ubuntu 14.04.3 LTS)</code> with <code>PHP 7.0.15</code></p>
  
  <p>I get the following error:</p>
  
  <pre><code>Your requirements could not be resolved to an installable set of packages.
  
    Problem 1
      - Installation request for magento/product-community-edition 2.1.3 -&gt; satisfiable by magento/product-community-edition[2.1.3].
      - magento/product-community-edition 2.1.3 requires ext-gd * -&gt; the requested PHP extension gd is missing from your system.
  
    To enable extensions, verify that they are enabled in those .ini files:
      - /home/ubuntu/.phpbrew/php/php-7.0.15/etc/php.ini
    You can also run `php --ini` inside terminal to see which files are used by PHP in CLI mode.
  </code></pre>
  
  <p>I tried to do the following installation on <a href="https://stackoverflow.com/questions/34367917/install-php70-gd-on-ubuntu">install php70-gd on ubuntu</a> but I still get the same error afterwards.</p>
  
  <p>How will I successfully install magento 2?</p>