Fix SVN commit change parser for files moved from deleted directory

Summary: This is not perfect. Moved files are reported as deleted but I'm happy with it.

Test Plan: Reparsed two commits which was previously wrong, now semi-correct.

Reviewers: epriestley

Reviewed By: epriestley

CC: aran

Maniphest Tasks: T1114

Differential Revision: https://secure.phabricator.com/D2215