fix ocramius/proxy-manager dependency version

Symfony 2.5 and higher requires ocramius/proxy-manager 0.4.0 or
higher.
Merge branch '2.5' into 2.6

* 2.5:
  Fix failing tests after merge
  fix ocramius/proxy-manager dependency version
Merge branch '2.6' into 2.7

* 2.6:
  Fix failing tests after merge
  fix ocramius/proxy-manager dependency version