Wait for keystone to become ready for floatingip creation

Wait for keystone service to become ready otherwise
haproxy reload can lead to haproxy returning
empty response and thus nova-floating-range provider
can not authorize with nova.

Change-Id: I8f9623411990679560b1694569dbb185883c4733
Closes-bug: 1351253
Closes-bug: 1348171
Merge "Wait for keystone to become ready for floatingip creation" into stable/5.0