Add .arcconfig

Summary: Add .arcconfig to repo

Test Plan: Needs no testing

Reviewers: DDRKirbyISQ

Differential Revision: http://phab.local/D2
Add .arcconfig

Summary: Add .arcconfig to repo

Test Plan: Needs no testing

Reviewers: DDRKirbyISQ

Reviewed By: DDRKirbyISQ

Differential Revision: http://phab.local/D2