[skeleton] Update Debian packaging template Here are multiple updates to the Debian packaging template provided when running `cubicweb-ctl newcube`: * Switch to source format 3.0 (quilt). * Switch to debhelper 9. * Switch to dh-python. * Add Python 3 packages. * Name the binary packages `python-cubicweb-CUBENAME` and `python3-cubicweb-CUBENAME` instead of just `cubicweb-CUBENAME` (which is still the source package). * Populate Depends using dh_python{2,3} support for Python requirements. * Run test suite at build time using pytest. * Add autopkgtest to run test suite against the installed package. * Bump Standards-Version to 4.3.0.

[test] Use --short-description when testing newcube command

[devtools] Allow to specify short desc on `newcube` command line In order to implement automated testing of `cubicweb-ctl newcube`, we need to avoid any user interaction. So we add a `-s` switch to specify a short description on the command-line instead of requiring an input.