Version 0.1.4

Soft-delete Submissions to reset student state

Previous methods of "deleting state" for a student had just issued
reset scores, so the (unscored) submission was still hanging around.
With this change, the submission can be "deleted" for all django-
relevant purposes, while still remaining in the database in case
it turns out to be interesting to analytics later.

Includes a migration that may take some time to run, and will acquire a
table lock. This will cause an outage for any other request trying to
hit the submissions table during the migration. We've estimated the outage
to last approximately 3 minutes on a database with 700,000 rows.

Test also included.

Update the DRF version requirement to match edx-platform

Add new app_label to ScoreAnnotation.

Django upgrade/1.8 release

Conflicts:
	setup.py
	submissions/models.py

We had made the migrations from master, but that isn't what edx-platform
was using yet.  This migration is re-made from 0.1.0, which removes
things that happened after 0.1.0.

remove deprecation warnings

Update the submission version.

Add the ability to annotate scores.

Upgrade djangorestframework to v3.1

update django-nose

* Upgrade DRF to v3.1
* Use JSONField on the model instead of custom serializer field for the submission answer.

Upgrade django-model-utils to 2.3.1

Update pytz to reflect upstream version change

In certain circumstances the version of Pytz in this file will conflict with versions of pytz required by edx-platform in `requirements/edx/base.txt`. This PR makes the version in this repository match.

Upgrade django-extensions to 1.5.5

Add get_all_submissions method to the API

This is consistent with the default ordering of the model and avoids ties in
case to items have the same timestamp.