File _constraints of Package votca

<?xml version="1.0" encoding="UTF-8"?>
<constraints>
  <hardware>
    <memory>
      <size unit="G">6</size>
    </memory>
    <memoryperjob>
      <size unit="M">1000</size>
    </memoryperjob>
  </hardware>
  <sandbox>kvm</sandbox>
</constraints>