[Resources] make SymfonyRequirements detect Zend Optimizer+ extension when using a Zend Server stack
merged branch hhamon/zend_optimizer_plus (PR #99)

This PR was merged into the 2.2 branch.

Discussion
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[Resources] make SymfonyRequirements detect Zend Optimizer+ extension when using a Zend Server stack

Commits
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b826452 [Resources] make SymfonyRequirements detect Zend Optimizer+ extension when using a Zend Server stack