Removed Django<2.2 support, Added Python3.8 support

Merge pull request #458 from edx/awais786/fixing-typing-issue

Fixing the typing package issue on py3.8

Django 2.0, 2.1, and 2.2 Compatibility

Django 2.0, 2.1, and 2.2 compatibility.

Decode request body from bytes to unicode.

Pass unicode to json.loads. (#428)

In python2 there was auto-coercion happening here but in python3 we need
to pass in unicode and requests body is bytes.

Add a feature to Mixologist

Mixologist can now take class objects and string class paths as input.

xblock-1.1.1

Adds ability to auto-deploy to PyPI from Travis on creation of new tags.

xblock-1.1.0

Adds the CompletionXBlockMixin and testing improvements.

xblock-1.0.1

Merge pull request #365 from edx/efischer/play_nice_with_py27

remove unicode literals

Support Python 3.

This release now verifies that tests pass under both Python 2 and Python 3.

Add ScorableXBlockMixin

Created a new mixin to encapsulate scorable block functionality.

This mixin provides:

• A consistent interface for retrieving and setting scores on the block, and calculating new scores.
• A generic implementation of rescore functionality using that interface

Consume Fragment class from the new web-fragments library

Merge pull request #359 from edx/andya/use-web-fragments

Separate Fragment class out into new web-fragments package