Reorganizing and refactoring old code.
Removing using . in keys to traverse nested ads.

This turned out to be more trouble than it was worth.  It made
marshalling maps with keys with dots in the name (e.g. emails or
domains) impossible. Besides, it is generally bad practice to access ad
members directly.
Reorganized project, added get command.
Merge pull request #12 from bwross/master

Reorganization + "get" command