R1:80f479d94812

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…