Code review comment for lp:~qzhang/lava-dispatcher/fix-861115

when execute lava-dispatcher, it reports errors as below:

$ ./lava-dispatch doc/lava-android-test-leb-panda.json
Traceback (most recent call last):
  File "./lava-dispatch", line 59, in <module>
    job = LavaTestJob(jobdata, oob_file)
  File "/tmp/fix-861115/lava_dispatcher/__init__.py", line 42, in __init__
    self.job_data)
  File "/tmp/fix-861115/lava_dispatcher/__init__.py", line 125, in __init__
    self._client = LavaAndroidClient(self, device_config)
  File "/tmp/fix-861115/lava_dispatcher/android_client.py", line 33, in __init__
    self.android_result_dir = mkdtemp(dir=self.context.lava_result_dir)
  File "/tmp/fix-861115/lava_dispatcher/__init__.py", line 149, in lava_result_dir
    if self.client.android_result_dir:
  File "/tmp/fix-861115/lava_dispatcher/__init__.py", line 133, in client
    return self._client
AttributeError: 'LavaContext' object has no attribute '_client'
18:13:45 liuyq:fix-861115$