make upgrade-glance do the minimal possible changes for upgrade

we only need to copy over paste configs, and add 1 conf variable to
each conf file.

Change-Id: I17a5bc4439bb03a0b5a6518fe6e33e1280bbf85f
don't regenerate keys for keystone

keystone doesn't need keys regenerated after it's upgraded, so
don't do that in grenade.

Change-Id: I5d2bd1b0910b2913769624356891556318b0e4c2