Add keystone::client

This class installs the keystone client package.

Change-Id: Ia410f92dc4fd8eee4e912b9387e4538bb7607a09
PKI should be the default token_format

Change-Id: I01105f594dac94536b9b436f92870acd9d5ab01a
Merge "PKI should be the default token_format"
Ensure pki_setup not run before configuration complete

Change-Id: I81bee474866c0a3c3786fcf1ab025163cbdc3ac9
Retry when keystone server refuses connections

Add an additional error type to avoid keystone client queries erroring
out while keystone server is being restarted

Change-Id: I5e3dd598af6f5bd72eae51f354ddde3cb0c0e07d