[ticket/11996] Add explanation how to correctly remove and update an extension

See http://area51.phpbb.com/phpBB/viewtopic.php?f=81&t=44001 for more
information about the decision.

PHPBB3-11996
[ticket/11996] Use a table for better styling

PHPBB3-11996
[ticket/11509] Fail on Travis CI if commit messages are improperly formatted.

PHPBB3-11509
[ticket/12151] Remove old dependency from profile type in tests

PHPBB3-12151
Merge pull request #1989 from nickvergessen/ticket/12151

[ticket/12151] Remove old dependency from profile type in tests
[ticket/12154] Update schema files with lastest database schema

PHPBB3-12154
Merge remote-tracking branch 'github-bantu/ticket/11509' into develop-olympus

* github-bantu/ticket/11509:
  [ticket/11509] Fail on Travis CI if commit messages are improperly formatted.
Merge branch 'develop-olympus' into develop

* develop-olympus:
  [ticket/11509] Fail on Travis CI if commit messages are improperly formatted.

Conflicts:
	.travis.yml
[ticket/11985] Reorganise travis/install-php-extensions.sh

PHPBB3-11985
[ticket/11985] Enable APC on command line so it can be used by PHPUnit.

PHPBB3-11985
Merge pull request #1990 from nickvergessen/ticket/12154

[ticket/12154] Update schema files with lastest database schema
[ticket/11985] Don't try to install APC on PHP 5.5 or higher.

PHPBB3-11985
[ticket/11509] Perform commit message checking after PHPUnit (fixes path).

PHPBB3-11509
Merge pull request #1993 from bantu/ticket/11509-develop

[ticket/11509] Perform commit message checking after PHPUnit (fixes path...
[ticket/12156] Add missing passwords manager to oauth

PHPBB3-12156
Merge pull request #1991 from marc1706/ticket/12156

[ticket/12156] Add missing passwords manager to oauth
[ticket/11996] Remove note until we really do disable the board

PHPBB3-11996
Merge pull request #1942 from nickvergessen/ticket/11996

[ticket/11996] Add explanation how to correctly remove and update an extension
[ticket/11880] Break up schema changes in the migrator

PHPBB3-11880
[ticket/12159] Fix codesniffer complaints due to profilefields and passwords

The two PRs regarding profilefields and passwords manager that were recently
merged caused a few codesniffer complaints that are fixed by these changes.

PHPBB3-12159