[ticket/11920] Add MariaDB environment to Travis-CI.

PHPBB3-11920
[ticket/11920] Have to use empty root password otherwise db creation fails.

PHPBB3-11920
Merge pull request #1780 from bantu/ticket/11920

[ticket/11920] Add MariaDB environment to Travis-CI.
[ticket/11920] Actually call travis/setup-mariadb.sh.

PHPBB3-11920
[ticket/11920] Manually purge mysql-common.

PHPBB3-11920
[ticket/11920] Print MariaDB version after successful setup.

PHPBB3-11920
Merge pull request #1782 from bantu/ticket/11920

[ticket/11920] Actually call travis/setup-mariadb.sh.
[ticket/11951] Add MariaDB to supported DBMSes in requirement section.

PHPBB3-11951
[ticket/11951] Add MariaDB to platforms we test on.

PHPBB3-11951
Merge remote-tracking branch 'github-bantu/ticket/11951' into develop-olympus

* github-bantu/ticket/11951:
  [ticket/11951] Add MariaDB to platforms we test on.
  [ticket/11951] Add MariaDB to supported DBMSes in requirement section.
[task/github-readme/travis] Fix Travis-Badge and link

PHPBB3-11968
Merge branch 'task/github-readme/travis' into develop-olympus

* task/github-readme/travis:
  [task/github-readme/travis] Fix Travis-Badge and link
[ticket/11920] Pin MariaDB repository to avoid conflicts with Ubuntu MySQL.

PHPBB3-11920
Merge remote-tracking branch 'bantu/ticket/11920' into develop-olympus

* bantu/ticket/11920:
  [ticket/11920] Pin MariaDB repository to avoid conflicts with Ubuntu MySQL.
[ticket/11970] Add set -x to Travis setup scripts.

Output is hidden by Travis by default and this will allow easier debugging.

PHPBB3-11970
[ticket/11970] Make apt-get less quiet.

PHPBB3-11970
Merge remote-tracking branch 'github-bantu/ticket/11970' into develop-olympus

* github-bantu/ticket/11970:
  [ticket/11970] Make apt-get less quiet.
  [ticket/11970] Add set -x to Travis setup scripts.
[ticket/11814] Remove redundant text from the topic reply email notification.

PHPBB3-11814
Merge remote-tracking branch 'prototech/ticket/11814' into develop-olympus

* prototech/ticket/11814:
  [ticket/11814] Remove redundant text from the topic reply email notification.
[ticket/12037] Fix hard-coded text in acp_inactive.html.

PHPBB3-12037