Always save minion key in open mode.

Instead of ignoring auth in open mode, save the key, since it's actually used
to encrypt stuff, and the minion won't be able to decrypt it if a different
key was used.
Make minion ID caching configurable

Conflicts:
	salt/config.py
This should be fine, but use safe_load just in case
handle no gid being passed in
don't compare on Windows
remove extra :
Merge pull request #8498 from UtahDave/0.17

Fix Windows User state
Update version to 0.17.2
Better `exec()` detection. Avoids esky build `NameError`.