Updates to project template for 0.12.0

The plan will be to merge these changes to the release-0.12.0 branch
once ready. Before releasing RapidSMS 0.12.0, tag the tip of this
release-0.12.0 branch as '0.12.0' so that users can choose this
version specifically for use with RapidSMS 0.12.0.  Then merge all
the changes to master and continue development there.

Branch: update-for-0.12.0
Updates from code review

- move templates under {{ project_name }} directory
- don't install locations app by default
- move default app to end (and add a comment to keep it there)
Another try at PROJECT_ROOT and PROJECT_PATH

PROJECT_ROOT is the top dir containing things for this project,
PROJECT_PATH is a subdir with the settings, wsgi.py, etc.

Added some comments to explain.

Wrote `PROJECT_PATH = os.path.join(PROJECT_ROOT, '{{ project_name }}')`
instead of `PROJECT_PATH = os.path.dirname(__file__)` because I thought
it made it a little clearer on reading it which directory we were
talking about, but it would work either way.
Merge pull request #4 from rapidsms/update-for-0.12.0

Update for RapidSMS 0.12.0