Unresolved issues/concerns for F26

[yuqi-zhang]

This issue will be used to track some errors/concerns that showed up on f26 cloud/atomic. The PR to "pacify" the tester is https://github.com/projectatomic/atomic/pull/1076 so we can start testing on f26, but the issues are as follows:

1. test_storage should possibly be reworked. The current test setup is conflicting with the new default of overlay as a driver. For now, the test for generated d-s-s is disabled.

2. some storage commands are still using "docker-storage-setup" instead of "container-storage-setup". There is a backward compatible check in place to pass tests for now, but the "storage" command should possibly be reworked since I don't think it is using c-s-s correctly (interaction between devicemapper and the default overlay configs).

3. some masked pylint errors should be further investigated

4. the expected checksums for dockertar-sha256-helper has changed. @giuseppe could you give some insight on why that may be the case?

5. keep the dockerfile for the project atomic tester image for now (bump to 26), since its a little easier and faster to set up with if a user wished to do a build with it. But perhaps it should be removed as we are no longer use the image in the tester, so there isn't a very good reason to keep maintaining it.

[giuseppe]

@yuqi-zhang https://github.com/projectatomic/atomic/pull/1079 should fix 4. Unfortunately the version of gzip/flate in golang1.8 produces a different output. We need to vendor the version in golang 1.6 so we can produce the same output