fix bug 1074201 - refactor test base classes and introduce some more

- this also fixes various issues with tests that improve speed and performance
- includes plenty of stylistic changes like PEP8 updates
bug 957802 - Readme: Use SVG badges.

Those badges look better on 2x (and more) displays. They're also a smaller download.
Merge pull request #2784 from jezdez/bug1074201

fix bug 1074201 - refactor test base classes and introduce some more
Merge pull request #2783 from espadrine/patch-1

Readme: Use SVG badges.
fix bug 1054461 - make sure the "account connected" message only shows up if the account connection process is initiated on the edit profile page.
bug 1054461 - Fix notification message layout
Merge pull request #2787 from darkwing/bug1054461

Bug1054461
fix bug 1074734 - use Django's RequestFactory instead of redundant test-utils subclass
fix bug 1072633 - Add SessionAwareClient class to be able to use session in tests.
Merge pull request #2788 from jezdez/bug1074734

Fixed bug #1074734 and bug #1072633
Fix Bug 1071591 - Download description alignments

To keep headings aligned at the top I removed vertical-align:centre and to keep buttons aligned at the bottom I absolutely position them at the bottom in a space created by adding padding to the bottom of the description.

Also added a fix to keep the "headings" on a separate line on mobile since they look weird on the same line as the image.
fix bug 795272 - Convert non-breaking spaces in header ids to underscores
fix bug 1057291 - move dashboards app into kuma namespace.
Merge pull request #2785 from trevorhobson/bug795272

Bug 795272 - Convert non-breaking spaces in headers ids to underscores
fix bug 1072989 - use user factory more.
fix bug 1065965 - When disabled, saving buttons must have a clear "disabled" look

CKEditor buttons are now enabled/disabled appropriately.
Merge pull request #2744 from rubenvereecken/new-issue-1065965

fix bug 1065965 - When disabled, CKEditor saving buttons must have a clear disabled look
fix bug 1071083 - use assertRaiseMessage more instead of manually handling exception in tests.

Also uses the fail testcase method for false positives in a few places.
Merge pull request #2792 from stephaniehobson/BUG-1071591-download-desc-align

Fix Bug 1071591 - Download description alignments
Bug #1070001 - Re-organize stylus

- Switched from @import to @require.
- Files should now require the files they need rather than relying on an @import in a different file.
- Files in /include should not generate output.
- Tried to break files in main into sensible smaller pieces.
- Ran output file through css validator to try to catch errors, fixed what came up.