Add utilities for finding channels, releases and rules in packages.

Review Request #7725 — Created Oct. 22, 2015 and submitted — Latest diff uploaded

Information

rbpkg
master

Reviewers

This adds a handful of utility functions that make it easy to get data
on packages that match certain criteria, such as rules that match a
version and the current system, or the current release channel.

Unit tests were added for each of these cases.

Unit tests pass.

Used these in a custom command that tested this functionality.