replaced getExtension() to be compatible with PHP < 5.3.6

see: https://github.com/fabpot/PHP-CS-Fixer/issues/48
bug #258 replaced getExtension() to be compatible with PHP < 5.3.6 (jakejohns)

This PR was merged into the master branch.

Discussion
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replaced getExtension() to be compatible with PHP < 5.3.6

see: https://github.com/fabpot/PHP-CS-Fixer/issues/48

Commits
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5013cd1 replaced getExtension() to be compatible with PHP < 5.3.6