Issue #26

This commit adds Spreadsheet, Row, TableOfContents, and Attachment
models and their migrations, as well as a script for managing the django
models (manage.py). Configuration is split across two separate files for
django and flask, but this may change in future commits. Issue #26.

Spreadsheets, attachments, and tables of contents can now be uploaded
from the command line using manage.py. Issue #26.

As per discussion in issue #26 and over email correspondence, the plan
was to keep torquedata in Flask but use the Django ORM to interface with
postgres, keeping the option of migrating entirely to Django in the
future.

In practice, this presented some nontrivial issues. Since the data model
effectively *is* the application, torquedata would effectively become a
Django project that happens to use Flask to handle views and routing.
Support for non-standard Django projects online is minimal and
ironically requires more specific knowledge of Django's inner workings.
Torquedata's views are so dependent on the old pickling data model that
they will all have to be rewritten anyways, which means sticking with
Flask is an unnecessary complication.

A new Django app was created with `django-admin startproject`, and the
models and management commands were copied over.

Issue #26

Adds template model and several fields to other models. Replaces
TextField json hack with proper JSONField. Issue #26

Update admin commands to reflect changes made to models. Issue #26.

This commit rewrites every API endpoint except /search/<sheet_name>,
which requires further consideration as discussed in issue #45. Input
validation reserved for future commits; views will not fail gracefully.

This is related to issue #26

This is finishing up the existing work started by YaxelPerez. With this
commit torque now uses postgres and django for all API endpoints except
search and editing.

This is related to issue #26

With this commit torque's search API endpoint now uses postgres' Full
Text Search feature to perform search queries.

This resolves issue #26

This is a re-implementation of all edit functionality but now using
django and postgres