Commands to add new apt repos

[sdt]

There's no easy way to add apt repos into the image.

Something akin to install-debian and install-raspbian that effectively does add-apt-repository should suffice.

add-apt-repository comes from software-properties-common which will add ~200Mb to the already large image. Perhaps something like http://unix.stackexchange.com/a/45880 might be the go.