Proposed way to get the version via server/api call easily.

Instead of hard coding the api version and placing the distribution version in setup.py this moves the version string to server/pulp/\__init__.py as \__version__. The api_version and server_version (new) returned in StatusController are based off of \__version__ as is setup.py's version parameter. This also allows a running server to be aware of it's current version via:

```python
from pulp import __version__
```

**Note**: This was not tested well and should either be verified before accepting OR used as an example for implementation.