Possible patch to fix Ardour appdata

[Guido Aulisi]

Hi,
Nils in your pull request to fix Ardour appdata
https://github.com/Ardour/ardour/pull/261
there's a comment by x42 that says it would break bundle-scripts,
'revision' is expected in the 2nd line.

So I modified your first commit to let revision stay in the 2nd line,
as Paul suggested in the PR.

This patch should be applied after your
commit 0f1915a7162a0f64d01
AppData release tags need a date to be valid

I'm attaching my patch, maybe this could help accept the PR

Bye
Guido Aulisi