simple_tfjob_tests py3 version

[gabrielwen]

Adding python3 test version.

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This change is 

[coveralls]

Coverage remained the same at 96.512% when pulling 95788fd on gabrielwen:simple_tfjob_tests_py3 into 00ea3ec on kubeflow:master.

[jlewi]

@gabrielwen can we avoid creating more test code that uses test_util.TestCase and instead use pytest if we are creating new tests?

Instead of creating a new file simple_tfjob_tests_py3 can we either

• Get rid of the python 2 version or
• Use the six module to create a single version of the test which is py2 and py3 compatible?

[gabrielwen]

@gabrielwen can we avoid creating more test code that uses test_util.TestCase and instead use pytest if we are creating new tests?

Instead of creating a new file simple_tfjob_tests_py3 can we either

• Get rid of the python 2 version or
• Use the six module to create a single version of the test which is py2 and py3 compatible?

@jlewi

ok, I'm getting rid of python2 version. will have another follow up PR to remove tf_job_client.py.

[jlewi]

/lgtm
/approve

[jlewi]

/lgtm
/approve

[gaocegege]

/approve

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

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