Merge branch 'ticket/11527' into ticket/11526

* ticket/11527:
  [ticket/11527] Upgrade composer.phar to 1.0.0-alpha7.
[ticket/11526] Increase composer minimum stability in olympus to stable.

PHPBB3-11526
[ticket/11526] Update all dependencies / regenerate composer.lock.

PHPBB3-11526
Merge pull request #1393 from bantu/ticket/11526

[ticket/11526] Increase composer minimum-stability from beta to stable