ResNet argparse fixes.

[robieta]

As noted, imagenet can no longer just use the default number of train_epochs. This PR explicitly sets it back to 100, and also fixes a bug related to "-h" being inadvertently caught by tf.app.run().

[karmel]

(1) The default should be set for Cifar too.
(2) This is a lot of extra boilerplate to add, just for the sake of running a test, especially considering that most people looking at this code will never see the tests at all. I think either having a parse_args function that gets called before tf.run, or better still just have the test create the class arg parser itself and call main, makes more sense. Remember, most users will just want to read once and run, not understand all of our testing and infra.

[robieta]

@karmel The more I look at it I'm inclined to just drop tf.app.run() altogether in favor of just:

if __name__ == "__main__":
  main()

It appears to be primarily for arg parsing, so we basically have 2 arg parsers stepping on each other's toes. From what I've read it's not a necessity.

[robieta]

Removing tf.app.run significantly simplified the amount of "counter magic" needed.

[karmel]

Do we still need this at all if we're calling main directly?

[robieta]

The end to end test passes its own args instead of using sys.argv. I suppose we could also just make argv a required arg. Typically this argv=None pattern is what I've seen.

[karmel]

I think it's more conventional then to have the if name == section pass in sys.argv, rather than having this extra line here.

[robieta]

The argv call is now in the ==main section.