[ticket/11531] Add basic set of functional tests for new avatar system

This currently includes tests for the gravatar, remote avatar, and upload
avatar drivers. The local avatar driver is currently not supported. Two
tests currently fail and have been marked as incomplete. One failure is
due to an issue with Symfony's DomCrawler that exists in Symfony < 2.2.
The other one is caused by a bug in the way remote avatars are treated.
According to my tests, this bug also exists in phpBB 3.0.11 and has been
reported in the tracker: http://tracker.phpbb.com/browse/PHPBB3-11534

PHPBB3-11531
[ticket/11531] Add acp and ucp groups functional tests for avatars

The test for the acp and ucp groups settings are currently marked as
incomplete due to a bug that causes the settings to not show an error
when incorrect data is entered. However, the avatar data is not saved.
That means that even though the error treatment seems to correctly work,
the user is never informed of the issues with the submitted avatar data.

PHPBB3-11531
[ticket/11531] Use assertContainsLang() where possible

PHBB3-11531
[ticket/11531] Remove incomplete flags for tests after merging PR #1404

Issues should be fixed by the now resolved ticket PHPBB3-11535:
http://tracker.phpbb.com/browse/PHPBB3-11535

PHPBB3-11531
Merge branch 'develop' of https://github.com/phpbb/phpbb3 into ticket/11531
[ticket/11600] Increase code test coverage of avatar manager

Currently, not all methods and their possible behaviors are tested with unit tests.
Add them for better code coverage.

PHPBB3-11600
Merge branch 'develop' of https://github.com/phpbb/phpbb3 into ticket/11531
[ticket/11531] Add changes for supporting modified testing framework

Additionally, the groups avatar is deleted after the avatar tests in the
ucp groups page in order to prevent issues with other tests that expect
that no avatar has been set for the admin group.

PHPBB3-11531
[ŧicket/11600] Split get driver tests into tests for all and only enabled ones

PHPBB3-11600
[ticket/11600] Use local variable for $user in test_localize_errors

PHPBB3-11600
[ticket/11600] Use lowercase null and remove duplicate test cases

PHPBB3-11600
Merge branch 'develop' of https://github.com/phpbb/phpbb3 into ticket/11600
[ticket/11600] Remove duplicate test case

PHPBB3-11600
[ticket/11620] Add testable facade for sessions.php

Since many functions in session.php have global variables inside the function,
this exposes those functions through a testable facade that uses testable_factory's
mock global variables to modify global variables used in the functions.

 This is using the facade pattern to provide a testable "front" to the functions in sessions.php.

 PHPBB3-11620
[ticket/11620] Add test for test_extract_current_page

PHPBB3-11620
[ticket/11620] Remove accidental argument from testable_facade.

PHPBB3-11620
[ticket/11620] Rename class_functions_test -> extract_page_test

Renaming this file because it is going to contain a large data provider,
so I'd rather split this test out.

PHPBB3-11620
[ticket/11620] Add data provider to extract_page

These test cases were taken from a live session,
more test cases should be added to test specific
functionality in this function.

PHPBB3-11620
[ticket/11620] Add extract_current_hostname

Add a tests for extracting the current hostname from session.

PHPBB3-11620
[ticket/11620] Fix quotes in extract_hostname_test

PHPBB3-11620