Display subnet cidr information in net-list

Fixes bug 1074415

This commit introduces extend_list() in ListCommand class. This method
can be used to update a retrieved list (e.g., add additional information
or convert some field to more human-readable value).

Change-Id: Icf5ab616ab4d9add16c921e1944ba37b376b2ab2
Allow known options defined after position arguments.

We run the argument parser to split known options and unknown options.
Make '-' work and have the same effect as '_' in both known and unknown
option parts.
Make metavar Uppercase.

blueprint options-location

Change-Id: Ic27b278484133c8b83e3b031a0810a76b050219f
Merge "Display subnet cidr information in net-list"