This will stop failures in list creation from displaying doule error messages

* start/stop isolated mailman instance when running tests in mailman_api_tests dir. ...

* initialize mailmanclient.Client with test credentials when running tests
* removed client attr from MailmanRESTManager; uses get_client instead

- removed abandoned view function (preferences) ...

- user_mailmansettings is now class-based and lives in views/user.py

Slightly improved messages for when the REST API isn't available, telling people to start Mailman core. The wording here could probably use some improvement, but this should be more helpful in the meantime.

Bug #1004052 - Display confirmation on list settings update

* added pagination on members view ...

* changed settings page

Have top page invite superuser to create a domain if none exist yet.

Adding a 'blank' settings page for when the user is not yet subscribed to any lists

* added success/error messages to moderator/owner form. ...

* removed some things pyflakes complained about.

* moved some sub navs to template tags ...

* generic MailingListView now detects list owners/moderators even if those permissions are not required
* fixed some permission bugs in the list navigation
* changes to the list member page:
    - list owners and moderators
    - "add owner" feature
    - "add moderator" feature
* several layout changes:
    - sub navigation items now have an "active" state
    - changed backgrounds of page and content containers
* added "add owner" feature
* added "add moderator" feature
* several text changes