[ticket/12741] Change the mode of the socket file

Since php 5.4.29, by default, php-fpm creates the socket with the 0600 mode
instead of 0666.

PHPBB3-12741
Merge pull request #2622 from Nicofuma/ticket/12741

[ticket/12741] Functional tests on Travis fail since php update last night

* Nicofuma/ticket/12741:
  [ticket/12741] Change the mode of the socket file
Merge branch 'develop-olympus' into develop-ascraeus

* develop-olympus:
  [ticket/12741] Change the mode of the socket file
[ticket/12726] PSR2.Namespaces.NamespaceDeclaration

PHPBB3-12726
[ticket/12726] Ensure PHP files do not contain any unused use statements

PHPBB3-12726