Add changes for longer names.  This will get backed out once it
makes it in to edx-pylint.

TNL-3425

It's silly to have to shut up pylint for "class Meta" all the time.

This gets us checking for tests inheriting from other tests.  When that
happens, tests get run more than once, which is pointless.  We have a
few dozen new warnings due to this new check.

This also disables unused-wildcard-import.  That removes a few hundred
warnings.

Together, this means we can reduce the pylint limit to 5999. :)

So far, it checks:

* Whether setUp is called in TestCase setUp methods.
* If _("translate me") functions are called with only string literals.

This reverts commit a92ca9d7.

[PLAT-217]

third_party_auth contains a working settings mechanism, the start of the provider interface + 3 implementations (Google, Mozilla Persona, LinkedIn), and a stub for the auth pipeline. Modified existing lms settings files to use but deactivate the module.

We had a bug where mixins weren't being applied before `load_from_xml`
was called. This meant that not all of the fields were being loaded
correctly. To fix it, we used the mixoligist from the runtime to apply
the mixins earlier in the process. However, that caused the mixins to be
applied twice.

The included fixes to xblock resolved the multiply-applied mixins, and
the fixes to the parsing code make it simpler to understand, and add
some unit tests of the parsing to boot.

Cleaned up files with muliline imports

Cleaned up files that do not use these imports

Misread comment

No one reads the pylint reports, we just want the messages.
setUp and tearDown don't need docstrings.
More ways to mark arguments as unused.

More tweaks

The most common error is Amazon SES having blacklisted an email address.
However, we handle any error being raised during user.email_user.

Fixes JIRA LMS-131

Start linting envs files, add task to only pylint errors, and move pylintrc file to the correct location