core: VURTI - use ResourceManager instead of commands

Use ResourceManager instead of direct command invocation
Add List, GetVmStats and GetAllVmsStats to the list of Command Types
Clean-up the code expressions, format, indent etc

Change-Id: I16359bf4af4968c8e9d8a650fb2af541ae0cc3fb
Signed-off-by: Roy Golan <rgolan@redhat.com>