Fixed #19896 -- Committed after clearing cache in the database.
Removing unneeded tearDown code.
Add sqldropindexes to manage

Change patch from https://code.djangoproject.com/ticket/5568
to work on modern Django.
Add special case for MySQL which has different syntax for DROP INDEX.
Add unit tests for the new functionality.
Revert "fixes #19263" - Fails if not SQLite

This reverts commit 2b76f19f2b89ac96bae2a169d71b23553c8101c7.
Made changes asked in review by HonzaKral

Add documentation for new command in django-admin.
Merge pull request #817 from rybaktomasz/ticket_5568

Fixes #5568 -- DROP INDEX subcommand
Fixed a few ResourceWarnings.
Fixed #11295: If ModelAdmin.queryset returns a filtered QS don't require a 2nd count call

Original patch rewritten, added tests and get_filters_params method for ChangeList class.
Thanks Alex for the report.
URL-encoded URLs in FlatPage.get_absolute_url.
Fixed #18862 -- Honored script prefix in FlatPage.get_absolute_url.
Merge pull request #820 from viciu/11295

Fixed #11295: If ModelAdmin.queryset returns a filtered QS don't require a 2nd count call
Fixed #19891 - Travis CI support
Documentation on continuous integration.

How to use a CI servers while contributing to
Django. Related to #19891 - Travis support.