New script in kdesdk/scripts: reviewboarddiff

[Aurélien Gâteau]

Hi,

Following a request from the GIT BoF at Akademy, I added my
reviewboarddiff script to kdesdk/scripts. It makes it possible to
generate reviewboard compatible diffs from a git-svn repository.

Running "reviewboarddiff HEAD" prints out uncommitted changes, running
"reviewboarddiff HEAD^" prints out the latest commit.

It's a Python rewrite of a shell script I found in a place I can't
remember right now. If you recognize your code, add your name in the
copyright header.

Hope this helps,
Aurélien