Finally fix django-debug-toolbar on Heroku staging
Merge pull request #67 from sealevelresearch/fix-debug-toolbar-on-staging

Finally fix django-debug-toolbar on Heroku staging
Add database model CombinedPredictionObservation

This uses a custom SQL view written in the initial migration. The Django
model is "unmanaged" meaning it doesn't try to modify the database.

[#75795976]
First pass at /sea-levels/ endpoint

Much of this has been taken from the Prediction app. It uses very
similar view and serializer pattern.
Merge pull request #68 from sealevelresearch/add-combined-endpoint

First pass at /sea-levels/ endpoint
NOT WORKING: add django-extensions package

So that we can use `python manage.py runprofileserver`.

Also see
http://www.darkcoding.net/software/profiling-django-for-cpu-bound-apps/
for how to interpret the output.