title: php70-mongo install doctrine/mongodb-odm fails
body: <p>I try to install doctrine/mongodb-odm[1.0.5] over composer but drops me </p>
  
  <pre><code>  Problem 1
      - doctrine/mongodb 1.3.0 requires ext-mongo ^1.5 -&gt; the requested PHP extension mongo is missing from your system.
      - doctrine/mongodb 1.2.2 requires ext-mongo ^1.2.12 -&gt; the requested PHP extension mongo is missing from your system.
      - doctrine/mongodb 1.2.1 requires ext-mongo ^1.2.12 -&gt; the requested PHP extension mongo is missing from your system.
      - doctrine/mongodb 1.2.0 requires ext-mongo ^1.2.12 -&gt; the requested PHP extension mongo is missing from your system.
      - doctrine/mongodb-odm 1.0.5 requires doctrine/mongodb ~1.2 -&gt; satisfiable by doctrine/mongodb[1.2.0, 1.2.1, 1.2.2, 1.3.0].
      - Installation request for doctrine/mongodb-odm ~1.0.5 -&gt; satisfiable by doctrine/mongodb-odm[1.0.5].
  </code></pre>
  
  <p>mongo extension is already installed </p>
  
  <pre><code>php -i | grep mongo
  
  /usr/local/etc/php/7.0/conf.d/ext-mongodb.ini
  mongodb
  mongodb support =&gt; enabled
  mongodb version =&gt; 1.1.6
  mongodb stability =&gt; stable
  libmongoc version =&gt; 1.3.5
  mongodb.debug =&gt; no value =&gt; no value
  </code></pre>
  
  <p>what went wrong in this case?</p>