Handle a corner case with recognition better

If we run a series of recognition requests and answer one correctly, and then hang up in the middle of the second (or otherwise cause the recognition to return in the 'INTERRUPTED' state) the complete method reads the old value for RECOG_COMPLETION_CAUSE and attempts to parse an empty string, throwing an exception. Handle a message coming back from a recognition request that is in the 'INTERRUPTED' state in a manner that doesn't cause an unchecked exception to be thrown (thus crashing the call and preventing any post-call actions from occurring)

cc @jared-prime @sfgeorge