Release 7.0.0

[roycaihw]

Merged master branch into release-7.0 branch, and updated version constants to auto generate 7.0.0 client.

Only the most recent two commits are new (updating constants and regenerating client). The other commits come from merging master branch on top of release-7.0 branch.

/cc @yliaog

[roycaihw]

@yliaog As we discussed #598 I removed the custom_object API change from the GA release. I need to put some hack in release-7.0 branch to mask the API change from client generation: dd4834f. The resulting client generation contains only version constant updates:

$ git diff HEAD~1 --stat | wc -l
    1181
$ git diff HEAD~1 --stat | grep "| 2 +-" | wc -l
    1176
$ git diff HEAD~1 --stat | grep "| [013-9]"
 kubernetes/README.md                                                | 4 ++--
 kubernetes/client/api_client.py                                     | 4 ++--
 kubernetes/client/configuration.py                                  | 6 +++---
 setup.py                                                            | 4 ++--

[yliaog]

/lgtm

[roycaihw]

Tests are green. Merging