Change Symfony version (2.3.1 -> 2.3.4) in php composer command line.
merged branch Gerfaut/patch-1 (PR #87)

This PR was merged into the master branch.

Discussion
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Change Symfony version (2.3.1 -> 2.3.4) in php composer command line.

Commits
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b57de25 Change Symfony version (2.3.1 -> 2.3.4) in php composer command line.