Updated catalog viewer creation logic

The logic for creating viewers has been moved to the view. This allows us to correct the data passed to the serializer when the viewers field is set to a comma-delimited list (e.g. for Swagger).

 ECOM-4489

Ignoring invalid data from the Drupal API

ECOM-4414

Multiple small fixes

- Using localhost instead of 127.0.0.1 because, strangely, 127.0.01 no longer works on my machine.
- Removed useless ELASTICSEARCH_URL and ELASTICSEARCH_INDEX_NAME settings from base.py

Update active courses to exclude runs whose end date has passed

Fixed a link to the Elasticsearch site.

Added permissions to the Affiliate Window viewset

The same permissions for the catalog endpoint are now enforced for the Affiliate Window endpoint.

ECOM-4481

Updated data loading code

- Management command now retrieves JWT access tokens
- Data loaders now properly initialize API clients with the correct authentication mechanism

 ECOM-4414

[SOL-1772] Add seat type query API endpoint

Added support for course run search

- Users can now query course runs
- The preview page has been repaired

ECOM-4275

Add referral help text.

Add acceptance tests for affiliate cookie tracking.

ECOM-4329

Replaced python-memcached with pylibmc

python-memcached doesn't work consistently with Python 3.5.

ECOM-4370

Add tracking parameters to marketing URLs.

ECOM-4331

Create users as catalog viewers.

Affiliate Window Datafeed

Creating end-point for Affiliate datafeed window.

Updated production.py to update JWT_AUTH

Added python-memcached requirement

ECOM-4370

This is necessary for caching.

ECOM-4370

Removed pinned version of python-social-auth

- Simplified logic by taking advantage of built-in PSA code
- Updated user model tests and removed django_dynamic_fixture