Class MultiKeyValueAction will be used to parse arguments like this:
--route destination=xxx,gateway=xxx --route destination=yyy,gateway=yyy
The result is a list like this:
[{destination:xxx, gateway:xxx}, {destination:yyy, gateway:yyy}]
This action also contain validation of the parameters.
Change-Id: Ie3aa8635c6a13fc2e429fe6922acd681dc7244cf