JERSEY-1964: NPE with Jersey 1 + Jackson 2 JAX-RS JSON provider

 - Fix in CommittingOutputStream (not invoking close/flush if not committed).
 - Integration test.

Change-Id: I8535e92f7fa1cda3fbee7d647ef5c779261d6c56
Merge "JERSEY-1964: NPE with Jersey 1 + Jackson 2 JAX-RS JSON provider"