Update importlib imports to use Python's version instead of Django's.

Review Request #8678 — Created Jan. 29, 2017 and submitted — Latest diff uploaded

Information

Djblets
release-0.10.x
d6279cf...

Reviewers

Modern versions of Django no longer ship a backwards-compatibility
module for importlib, since Python 2.7 provides this, and is the minimum
version required by Django. Djblets 0.10 also requires Python 2.7, so we
can safely rely on Python's version of this module, getting us a step
closer to compatibility with modern versions of Django.

Unit tests pass against Django 1.6.

These failures no longer show up on unit tests against Django 1.10.