When trying to see files or view diff between files from a branch that has
been marked as deleted (like a reintegrated feature branch), websvn
displayed an error saying that file does not exist at that specific
revision, even though it actually does. Adding peg=<rev> fixes this.

Reference: ticket http://leetcode.net/mantis/view.php?id=237

Fixes #6

Signed-off-by: Damien Regad <damien.regad@merckgroup.com>