first pass at new yum distributor migration
added clearing of orphaned parent publish directories; added docstrings
initial start on unit tests for migration script
unit tests and some bug fixes
refactored tests due to re-importing migration module does not load new module from disk
using get_collection directly
circumventing managers publish to avoid having to dynamically load all plugins
added reading of new distributor conf
added removal of legacy root publish directories
Merge pull request #425 from pulp/jconnor-yum-distributor-migration

Jconnor yum distributor migration