Rebranded to only manage AO auth.

Renamed plugin to auth_association_online:
 * Changed logging calls
 * Renamed functions
 * Removed doc comments referring to google
 * _Retained_ all copyright and license notices from original author

Removed travis config, as we don't use travis.

Removed test files, as we will not be running automated tests against this, and
we don't want to have to make sure that the tests written for google/linked-in/etc
work with the new "AO" plugin.

Linked users based on additional "associationOnlineId" field, rather than email.
Incorporate the site-uuid from AO into user identification.

This manages the situation where multiple AO sites want to use
the same mooble installation. This isn't possible now, but doing
this now makes it available as an option in the future.
Correctly prefix user_info_data table before selecting.