Track path moves in Owner's packages

Summary:
Currently, if a package is moved from one location to another those package paths become stale in Owner's packages.
This diff fixes that by tracking the path moves in diffusion commit messages and updating the owners package paths accordingly.

Test Plan:
Tested the script by running the reparse.php script on the following test commits:
https://phabricator.fb.com/rPHGITd7271a2de212e0b2de33d485b2ff806e75f73d36
https://phabricator.fb.com/rPHGIT0192fb41e7bd3e0faeeb14facdc7f7bea1b716d0

on the following packages:
https://phabricator.fb.com/owners/package/1167/
https://phabricator.fb.com/owners/package/1168/

Reviewers: nh

Reviewed By: nh

CC: aran, epriestley

Differential Revision: https://secure.phabricator.com/D3985