File _servicedata of Package swarm

<servicedata>
  <service name="tar_scm">
    <param name="url">https://github.com/ethersphere/swarm.git</param>
    <param name="changesrevision">cf4cefbd7adc4aeeea8182ffc0a6b0d91a8abcb7</param>
  </service>
</servicedata>