Lack of .version module attribute breaks various dependent li

[hypercodex]

The new version 3.0 seems to lack a version attribute on the module. Breaks libs that use this as a check.

See here Django Rest Framework checking for version:

from rest_framework.compat import postgres_fields, unicode_to_repr
  File "/home/zzz/.virtualenvs/project/lib/python3.6/site-packages/rest_framework/compat.py", line 161, in <module>
    if markdown.version <= '2.2':
AttributeError: module 'markdown' has no attribute 'version'

[facelessuser]

This is a duplicate of #709