this is the first patch in a series to actually make fernet the default
token provider in keystone. the patches for grenade, release notes, and
actually switching the value in keystone all depend on this patch first.
reasons for switching over:
- fernet tokens are the recommended token provider
- the install guide for newton recommends deployers use fernet tokens [0]
- we previously attempted this switch but ran into timing issues [1],
the timing issues have been resolved [2]
[0] http://docs.openstack.org/newton/install-guide-ubuntu/keystone-install.html
[1] 153db26970
[2] https://review.openstack.org/#/q/topic:make-fernet-default
Change-Id: I3b819ae8d2924f3bece03902e05d1a8c5e5923f1
dc486bc12f