Add scenarios that cover all events and traits Ceilometer API
All scenarios create new user in keystone to store new Event in Ceilometer.
create_user_and_get_event checks GET /v2/events/<message_id>
create_user_and_list_events checks GET /v2/events
create_user_and_list_event_types checks GET /v2/event_types
create_user_and_list_traits checks
GET /v2/event_types/<event_type>/traits/<trait_name>
create_user_and_list_trait_description checks
GET /v2/event_types/<event_type>/traits
Change-Id: I572730d9f69e3d63b29eeedd03ddc24071ffca3d