Monasca uses the deprecated identity v2 API to create its resources
during a devstack setup. This patch refactors the setup script in
order to conform to the v3 API.
Main changes:
1) use keystoneclient.v3 instead of keystoneclient.v2_0;
2) use keystoneauth's password plugin and session to instantiate the
keystone client. Currently monasca creates a ksclient with deprecated,
v2 parameters in order to get a token to get another ksclient - and then
perfom its operations. This is deprecated and should not be done;
3) reflect some v3 changes, e.g, pass the default domain when creating
a project; use the role assignments API; create one endpoint for each
interface (public, internal or admin) instead of only one endpoint.
4) conform to PEP8.
Change-Id: I56c1e7e8abd5e10695b6089a55cd3a16adeb2450
f8b7e0435f