Add extra error handling to DRT2 launcher script

  logging.info("Running the tests...")

  logging.debug("Command = %s" % cmd)

  (stdoutdata, stderrdata) = subprocess.Popen(cmd, shell=True, stdout=subprocess.PIPE, stderr=subprocess.PIPE).communicate()

  if stderrdata != "":

    logging.info("Failed to start tests:\n%s", stderrdata)

    return

  if re.search("^INSTRUMENTATION_STATUS_CODE: -1", stdoutdata, re.MULTILINE) != None:

    logging.info("Failed to run the tests. Is DumpRenderTree2 installed on the device?")

    return

  if re.search("^OK \([0-9]+ tests?\)", stdoutdata, re.MULTILINE) == None:

    logging.info("DumpRenderTree2 failed to run correctly:\n%s", stdoutdata)

    return

  logging.info("Downloading the summaries...")