WellManager's `get_current()` can now find Wells using `title` or `slug`.

In answer to armstrong/armstrong#74
The method takes kwargs for title or slug, but defaults to `title` if using an arg to maintain backward compatibility.
Merge remote-tracking branch 'joncotton/flexible_get_current'
Add a flexible get_current -- thanks @joncotton (v1.9.0)
Bump to next dev version
Update requirements to allow up to Django 1.4.3
Allow all versions of Django 1.3.x
Update to latest point releases for Django
Bump Django requirements to latest (v1.9.1)