Fixes #746 - Generate all the Host template when click on Build to avoid...

Generate all the Host template when click on Build to avoid errors during installation.
Includes moving of template_used to Managed model so it can be used elsewhere.

Expect (not stub) ```PowerManager::BMC.new(smart_proxies(:bmc))```, and make any instance of ```PowerManager::BMC``` return true for ```reset``` (stubbing :ok: here).