Fix various things - WIP (#241)

* Django 1.11.17 is required to work with python 3.7+ so make sure to install that.

* First pass at cleaning up the models some

Adding proper verbose_name and help_text for all fields.  Add validators to some as well.
Verified that manage.py test still passes.

This is a WIP though, it will need a migration before we're done.

* Fix flake8 errors

* Fix pydocstyle errors

*  Add migration, fix migration history, add tests around migrations.

Migrations were broken if you went backward and forward again, so I fixed the history with a new migration.  I then was able to properly add my own new migration.  Lastly, I added tests to try and ensure no migration issues happened again.

* Make raw sql a tuple format to avoid sqlparse requirement

* Must add absolute_import to every file for python2

* Don't have to clear our django's migration history, apparently it works fine without that.

* sqlite won't let you run things like migrations inside another transaction (like a test)

* Fix django 2.2 tests

* Setting TOXENV seems to no longer handle the django env variable, so just let it do one test with latest django.

* Run migration backward/forward for all tests

Author: liquidpele

.travis.yml

@@ -13,9 +13,7 @@ os:
   - linux
 matrix:
   include:
-    - {python: 3.7, env: DJANGO=1.11 TOXENV=python37, dist: xenial, sudo: true}
-    - {python: 3.7, env: DJANGO=2.0 TOXENV=python37, dist: xenial, sudo: true}
-    - {python: 3.7, env: DJANGO=2.2 TOXENV=python37, dist: xenial, sudo: true}
+    - {python: 3.7, env: TOXENV=python37, dist: xenial, sudo: true}
     - { python: 3.5, env: TOXENV=flake8 }
     - { python: 2.7, env: TOXENV=flakeplus }
     - { python: 3.5, env: TOXENV=pydocstyle }

django_celery_beat/migrations/0005_add_solarschedule_events_choices.py

@@ -7,14 +7,6 @@
 
 
 class Migration(migrations.Migration):
-    replaces = [
-        ('django_celery_beat', '0005_add_solarschedule_events_choices'),
-        ('django_celery_beat', '0006_auto_20180210_1226'),
-        ('django_celery_beat', '0006_auto_20180322_0932'),
-        ('django_celery_beat', '0007_auto_20180521_0826'),
-        ('django_celery_beat', '0008_auto_20180914_1922'),
-    ]
-
     dependencies = [
         ('django_celery_beat', '0004_auto_20170221_0000'),
     ]

django_celery_beat/migrations/0005_add_solarschedule_events_choices_squashed_0009_merge_20181012_1416.py

@@ -8,7 +8,6 @@ class Migration(migrations.Migration):
 
     dependencies = [
         ('django_celery_beat', '0006_periodictask_priority'),
-        ('django_celery_beat', '0008_auto_20180914_1922'),
     ]
 
     operations = [