Don't strip leading slashes for perforce diffs.

Review Request #5879 — Created May 26, 2014 and submitted — Latest diff uploaded

Information

Review Board
release-2.0.x
9c0d1b7...

Reviewers

Because perforce depot paths start with //, stripping a leading slash is a bad,
bad thing. I've moved the filename normalization into the diff parser, and
overridden it in the perforce specialization.

Ran unit tests.