Fix core version in drupal-org.make
This resulted in a packaging error on https://drupal.org/node/1983218
Packaging error messages
ERROR: hostmaster-7.x-3.x-dev specified an invalid 'core' attribute -- the core major version must match the API version of the release.
move hosting back to its own module
this decouples the releases of core from aegir, the same way we do
we also change the makefiles so that the makefile found by drupal.org
will use the tagged releases while our local makefile will use the git
releases. the trick here is that the hostmaster.make file is first
read by drush make everywhere *except* on drupal.org.