Make directories with spaces in their names work OK in diffusion end to end

Summary:
we were parsing the git log output slightly incorrectly and over-exploding on spaces. we also needed to escape the path %20 stuff`.

Not sure if there's something fancy to do given folks should reparse their repos if they are impacted by this issue.

Test Plan:
made a directory with spaces and some dummy revisions. observed diffs wouldn't load and links broken.
with patch, ran scripts/reparse.php for pertinent revisions and diffs loaded and links weren't broken.

Reviewers: floatinglomas, epriestley

Reviewed By: epriestley

CC: aran, Koolvin

Maniphest Tasks: T1252

Differential Revision: https://secure.phabricator.com/D2510