Allow batch handler to set http status

[jmccaull]

@oliemansm, another minor change - we found if we throw an exception the server will return 400, but if we try to write any sort of error message tomcat will not update the status preventing us from sending back 400 with any sort of message

[jmccaull]

I'm going to update the test to cover this case as well

[oliemansm]

@jmccaull Version 7.3.3 has been released.