Merge pull request #1392 from bantu/ticket/11527

[ticket/11527] Upgrade composer.phar to 1.0.0-alpha7.
Merge pull request #1393 from bantu/ticket/11526

[ticket/11526] Increase composer minimum-stability from beta to stable
[ticket/11513] Add PHPUnit 3.7 and DbUnit 1.2 as a composer dev dependency.

PHPBB3-11513
[ticket/11513] Update (all) composer dependencies.

PHPBB3-11513
[ticket/11513] Use PHPUnit from composer in .travis.yml.

PHPBB3-11513
[ticket/11513] Use composer install with --prefer-source to avoid openssl dep.

PHPBB3-11513