Add package_state to App api.

We need to be able to display the package_state for apps for use in an admin UI. This change exposes this additional field through the Cloud Controller api.

'package_state' will be returned by the API amongst the rest of the App details.
The package_state is read-only.

Travis build show as failing.....it actually passes for mysql but fails for postgres. I am trying to work out why, but i am not sure this is to do with my code, and actually might be to do with parallel processing of tests. Will update if I find anything but any guidance/comments would be much appreciated.