1. Fix calculation of base_path and path. Previous calculations would strip the username field from the repository and then use the length of that to calculate the base_path:
    svn://username@test.com/repo => svn://test.com/repo
                                    svn://username@test.com/repo/trunk
   base_path would then be calculated as ".com/repo/trunk" instead of "/trunk".
2. Allow users to specify a revision to diff against when posting reviews.

Two tests added, all previous tests pass.