restapi : JAXBMarshallingException are not propogated

When invalid xml is submitted to restapi, the
JAXBMarshallingException is not propogated to the
client.

Change-Id: I2a3913b4b063bc7cff3f972a68f8c5fb7fccc1a1
Bug-Url: https://bugzilla.redhat.com/1064572
Signed-off-by: Ravi Nori <rnori@redhat.com>
(cherry picked from commit 82e134f664243e0916985aba16eb709e588da2e6)