B-51215 - Repose Support Story - Translation race condition fix

Marshalling the request headers in translation was not done in a thread-safe fashion.  Potentially 2 requests could be marshalled at the same time with
the same marshalling object.  By synchronizing this call, this fixes the issue.
Merge branch 'master' of https://github.com/rackerlabs/repose
B-48943 - Update api-validator configuration to match translation when configuration  xsl-engine

Moving to api-checker 1.0.9.
Merge pull request #586 from usnavi/master

B-51215 - Repose Support Story - Translation race condition fix