NOT FOR MERGING: Fixes to pet detector tutorial

[maxwang7]

I went through the pet detector tutorial and made some fixes that got the training portion running. I haven't figured out how to get the evaluation code (there's an open issue for pycocotools) or the ipython notebook running. I don't have context on whether the fixes I made here were the correct ones, but they did get the program to the point where it was working for me.

I hope this contribution helps improve the quality of the tutorials in the future, thank you for maintaining this project!

[tensorflow-jenkins]

Can one of the admins verify this patch?

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[jlertle]

@maxwang7 do you happen to have a link for open issue with pycocotools regard the evaluation issues? Would love to track it as I can't seem to get coco_mask_metrics working.

[pkulzc]

Sorry I didn't get your purpose of this pull request.

1. Some of you files are outdated
2. It includes issues already fixed(BackupHandler)
3. It contains your personal gs address or other paths.

Do you simply want to keep this PR as a reference? In that case you should make your own branch instead of sending a PR.

Currently running on CMLE is not working due to tf runtime issue (temporary way is to use my gcp-1.2-ready branch) but running locally do not require any fixes.