Add the services module for API support

Hey @billtzim , the "services" Drupal module is needed for an "API" style support, to be consumed by mobile clients for example. The android client I've started (check out the client branch as well: https://github.com/OpenThessaloniki/PointsOfInterest/tree/hypest/android-client) is using the XML-RPC server.

For the services module, check out the instructions here: http://bitgriff.blogspot.ru/2013/02/drupal-with-android-integration-make_16.html