one of the problems we've got with tempest is the fact that config
loading is tied into the class hierarchy. However there is no
reason why it should be. If we instead create a config proxy
object we can lazy load the actual config when we are executing,
and not do it at import time.
This could use future iteration, but it does a huge job in
removing config from the object inheritance tree which massively
simplifies our ability to use config variables throughout the code.
Change-Id: I9b1bbfe231c85c01938bd68be4e5974bd24130d6
86bd8427e3