Fixed #21614 -- improved docs on configuring email for development.
Fixed E127 pep8 warnings.
Clarifed table rewrites in migration docs.

Small nitpicks. All column-related ALTER TABLE commands take an
exclusive table lock in PostgreSQL. The difference is that adding a
column without default doesn't cause a table rewrite, so the lock is
held only for a short time.

The time taken is more accurately proportional to table size, not row
count.
Fixed #21250 -- Made HTTP auth user header configurable in tests

Currently, if the authentication mechanism uses a custom HTTP header
and not REMOTE_USER, it is not easy to test. This commit modifies
remote user tests in order to make them more generic.
Revert "Allowed running GIS form tests that don't require spatial database"

This reverts commit 07fe0bf3f4a49a734f83f5ea30130449dacf9660.
This was not working properly on system without geos library
installed.
Fixed #21539 -- Added example of modelformset_factory's form argument
Added internal link to i18n documentation.
Typo in 1.7 release notes
Fix docs typo
Fixed #21621 -- Removed kqueue autoreloader.
Merge pull request #2079 from brutasse/master

Typo in 1.7 release notes
Fixed #21619 -- Made SingleObjectMixin.get_object catch a more precise exception.

Thanks to Keryn Knight for the report.
Added some internal links to render_to_string documentation.
Removed unnecessary call to force_text in utils.html.clean_html.

Refs #21574
Removed unnecessary function-level import.
Fixed #21564 -- Use local request object when possible in generic views.

Thanks to trac user adepue for the report and original patch.
Fixed #17413 -- Serialization of form errors along with all metadata.
Removed duplicated `TimeField` in __all__.
Moved django.db.models.loading to django.apps.cache.

This commit doesn't contain any code changes; it's purely a refactoring.
Removed BaseAppCache.app_store.

It was only storing redundant information. This is part of the effort to
allow applications without a models module.