Path to support OPTIONS verb when using rest interface via roundup-server. Also make sure rest interface doesn't hang when processing OPTIONS, DELETE, PATCH which don't have a payload by creating a CONTENT_LENGTH of 0 if these verbs are used and CONTENT_LENGTH is missing.

try:
    # Python 3+.
    from xmlrpc import client, server
    server.SimpleXMLRPCDispatcher
except (ImportError, AttributeError):
    # Python 2.
    import xmlrpclib as client
    import SimpleXMLRPCServer as server