Two fixes for software-properties, one security fix for 5.5, one bug fix for 6.0

The attached tarball contains the following 2 source packages:

software-properties_0.81.13.5+5.5trisquel1 which fixes a security issue, a possible MTM attack.

software-properties_0.82.7.3+6.0trisquel2 which fixes the add-apt-repositroy bug (you were not able to add a ppa with that command)