As seen in Bug #2045206 wait_for_endpoints can fails if keystone
is in a transient state. This change puts tenacity around the
keystone client setup to make it more resilient.
Closes-Bug: 2045206
Some endpoints (heat) return 401s if you try and access them
without authenticating. Given the ep has been able to verify
whether you are authenticated a 401 is ok for a rudementary
health check
* Add method to check OpenStack endpoints
Add method to check OpenStack endpoints are returning acceptable
http codes. This should be used with caution as a charm whould
indicate if its payload is not ready via workload status and
workload status messages
* Fix dox string
wait_for_cacert will wait for keystone to recieve and install
a cacert. This is particularly useful when the certificate
issuer is in a different model.