Adding missing network functions for debian_ip.py

Added missing definitions for networking setting, add and get.  
Changed interface parsing to use a dictionary for inet and inet6 interfaces instead of an array.  
Certain assumptions were made within the code on the order the ipv4 & ipv6 interfaces would appear, using a dictionary instead resolves some potential issues that could have popped up with an array.  
Removing the tests for ip.get_network_settings and ip.build_network_settings from the exclusion.