debian/watch: Update to track github tags.

Thanks: Bart Martens <bartm@debian.org> for the rewrite
debian/README.source: Update my own instructions.
Imported Upstream version 2013.05.14
Merge tag 'upstream/2013.05.14'

Upstream version 2013.05.14. We remove our own changes to avoid future
conflicts.

Conflicts:
	.gitignore
Update changelog.

Git-Dch: Ignore
Imported Upstream version 2013.05.23
Merge tag 'upstream/2013.05.23'

Upstream version 2013.05.23
Update changelog.

Git-Dch: Ignore
debian/watch: Download version specific for distributors.
Update changelog.

Git-Dch: Ignore