Refactor CLI commands to use new IIPCapability methods.
Fix bug - calling ipv4 methods when ipv6 addresses are given. Call ipv6 methods instead.
Define xml namespace in new api classes.

Defining the namespace is a requirement for CXF to successfully define the complete WADL of the service.
ListInterfacesCommand displays description even when the interface has no ip addresses.
Merge pull request #814 from isartcanyameres/features/unified-ip-rest-interface

Features/unified ip rest interface