Implement Database as a Service (Trove)

MySQL database :white_check_mark: 
Keystone resources :white_check_mark: 
Load-Balancer :white_check_mark: 
Common class :white_check_mark: 
Controller classes (API, conductor, taskmanager)  :white_check_mark: 
This is a first pull-request which aims for testing. Also, I don't see yet any RabbitMQ SSL support in this module (merged) at this time. Maybe it should be part of another pull-request, later.