passlib.ext.django: Updated UTs to work with latest django release

(should fix long-standing issue 98)

* test_ext_django:

    - Simplified "stock config" setup code.  It now gets it's "sha_rounds" value
      from the django source, so we don't have to manually update it every time
      django changes their default.  This should require less maintenance across
      minor django releases.  (Should fix issue 98, and prevent recurrence)

    - Updated tests to account for quirks in how encoded hashes are handled.
      Specifically: None, "", and invalid hashes all cause subtly different
      behaviors across django versions.  tests pass against django 1.8 - 3.1.

    - split "empty hash" test out from the loop it shared with "null hash" test,
      since the two behave differently.

* tox: expanded envlist to explicitly test a bunch more django versions
  (1.8 - 3.1); and remove some needless "django 2.x + py2" tests

* passlib.apps: reformatted django CryptContext declarations;
  added one for django 2.1 (which dropped "django_bcrypt" it's default list)

* passlib.ext.django:

    - added internal "quirks" helper as central place to track
      minor edge-case changes between django versions.

    - passlib_to_django() helper now falls back to searching hasher classes
      directly, even if patch isn't installed.  this allows it to work
      for django hashers that have been removed from django's default list.

2 files changed, 22 insertions, 8 deletions

diff --git a/docs/history/1.7.rst b/docs/history/1.7.rst
index 95d57f5..3a8250f 100644
--- a/docs/history/1.7.rst
+++ b/docs/history/1.7.rst
@@ -22,6 +22,10 @@ Bugfixes
 
 Other Changes
 -------------
+
+* :mod:`passlib.ext.django` -- updated tests to pass for Django 1.8 - 3.1 (:issue:`98`);
+  along with some internal refactoring of the test classes.
+
 * .. py:currentmodule:: passlib.context
 
   :class:`CryptContext` will now throw :exc:`~passlib.exc.UnknownHashError` when it can't identify
@@ -29,6 +33,12 @@ Other Changes
   Previously it would throw a generic :exc:`ValueError`.
 
 
+Deprecations
+------------
+
+* :mod:`passlib.ext.django`: This extension will require Django 2.2 or newer as of Passlib 1.8.
+
+
 **1.7.3** (2020-10-06)
 ======================
 
diff --git a/docs/lib/passlib.ext.django.rst b/docs/lib/passlib.ext.django.rst
index 51097cc..747c5e7 100644
--- a/docs/lib/passlib.ext.django.rst
+++ b/docs/lib/passlib.ext.django.rst
@@ -6,12 +6,6 @@
 :mod:`passlib.ext.django` - Django Password Hashing Plugin
 ==========================================================
 
-.. versionadded:: 1.6
-
-.. versionchanged:: 1.7
-
-    As of Passlib 1.7, this module requires Django 1.8 or newer.
-
 .. rst-class:: float-center without-title
 
 .. warning::
@@ -49,9 +43,19 @@ of uses:
     This plugin should be considered "release candidate" quality.
     It works, and has good unittest coverage, but has seen only
     limited real-world use. Please report any issues.
-    It has been tested with Django 1.8 - 1.9.
+    It has been tested with Django 1.8 - 3.1.
+
+.. versionadded:: 1.6
+
+.. versionchanged:: 1.7
+
+    Support for Django 1.0 - 1.7 was dropped; now requires Django 1.8 or newer.
+
+.. rst-class:: without-title
+
+.. warning::
 
-    (Support for Django 1.0 - 1.7 was dropped after Passlib 1.6).
+    As of Passlib 1.8, this module will require Django 2.2 or newer.
 
 Installation
 =============