Summary:
Create a new class for them, pass instance around as need.
This looks like it's mostly working, but I'd like to replace the various `new ArcanistConfigurationManager()`
calls with something more suitable.
And maybe get a better name for ArcanistConfigurationManager ("Configuration" is already taken).
Test Plan: arc unit --everything, and then some.
Reviewers: epriestley, #blessed_reviewers
Reviewed By: epriestley
CC: Korvin, epriestley, aran, chad
Differential Revision: https://secure.phabricator.com/D7271
