title: composer does not install mongodb ubuntu
body: <p>I ran: <code>composer require mongodb/mongodb</code>. But it gave me the following error : </p>
  
  <p>has error:</p>
  
  <blockquote>
  <pre><code>- mongodb/mongodb 1.0.1 requires ext-mongodb ^1.1.0 -&gt; the requested PHP extension mongodb is missing from your system.
  - mongodb/mongodb 1.0.0 requires ext-mongodb ^1.1.0 -&gt; the requested PHP extension mongodb is missing from your system.
  - Installation request for mongodb/mongodb ^1.0 -&gt; satisfiable by mongodb/mongodb[1.0.0, 1.0.1].
  </code></pre>
  </blockquote>
  
  <p>I tried : <code>composer show -p</code></p>
  
  <p>Then it gave me:</p>
  
  <pre><code>......
  ext-iconv           0         The iconv PHP extension
  ext-mcrypt          0         The mcrypt PHP extension
  ext-mhash           0         The mhash PHP extension
  ext-mongo           1.6.12    The mongo PHP extension
  ext-mysql           1.0       The mysql PHP extension
  ext-mysqli          0.1       The mysqli PHP extension
  ......
  </code></pre>
  
  <p>Why am I getting the error?</p>
  
  <p><code>php -m</code></p>
  
  <pre><code>..... 
  libxml 
  mbstring 
  mcrypt 
  mhash 
  mongo 
  mysql 
  mysqli 
  openssl 
  pcntl
  pcre
   PDO 
   .....
  </code></pre>
  
  <p>I'm using ubuntu 14.04 LTS</p>