Update klein Framework

Summary: HHVM reaches 100% for klein.php after applying https://github.com/chriso/klein.php/commit/744c07b7d4d168f146d0295073d85af13e576316
This is a good opportunity to update it.

I got 98.53% running it.
Closes https://github.com/facebook/hhvm/pull/4333

Reviewed By: @fredemmott

Differential Revision: D1700389

Signature: t1:1700389:1418420526:23740b8efe14af54cbeec4c1913462c488655474