fix bug 1056950 - only send welcome email when at least one email address is verified

This also delays sending the welcome email till after the initial email address confirmation has happened.
Merge pull request #2773 from jezdez/bug1056950

fix bug 1056950 - only send welcome email when at least one email address is verified
fix bug 1072921 - make sure some of the allauth tests are better isolated with regard to user object creation
Merge pull request #2775 from jezdez/bug1072921

fix bug 1072921 - make sure some of the allauth tests are better isolated with regard to user object creation
Bug 1072921: Add more isolation of allauth-related tests.

Two things going on here:

1. Expand the work done in 183fa261c7e7a8cce216b3f4977154a787ba124e to
   the test cases in test_templates.py. Although there's less going on
   in that file and so probably a lower risk of order dependence, we
   probably want more tests there later and so it's a good bit of
   future-proofing.

2. When a unique email address and/or username is needed for test
   isolation, instead of using sequential numbers use a name/address
   based on the name of the test method in which it's used. This will
   hopefully avoid issues down the road where we might lose track of
   which numbers had already been used in existing tests.
Merge pull request #2776 from ubernostrum/isolate-auth-tests-1072921

Bug 1072921: Add more isolation of allauth-related tests.
[fix bug 1073255] broken link on https://developer.mozilla.org/en-US/learn/css
Fix bug 1073300: Remove anonymous database docs
Merge pull request #2780 from openjck/1073300-remove-anonymized-database-docs-section

Fix bug 1073300: Remove anonymous database docs
Merge pull request #2779 from ckprice/bug-1073255-broken-link-css3-screencast

[fix bug 1073255] broken link on /learn/css
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
Merge pull request #2784 from jezdez/bug1074201

fix bug 1074201 - refactor test base classes and introduce some more
fix bug 1054461 - make sure the "account connected" message only shows up if the account connection process is initiated on the edit profile page.