[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.

^build$
^dist$
\.egg-info$
^.tox$
^.cache$
\.pyc$
\.pyo$
\.bak$
\.old$
\~$
\#.*?\#$
\.swp$
^doc/book/en/apidoc$
\.old$
\.pybuild
cubicweb/server/test/data/slapd.conf
debian/python-cubicweb
debian/*.log
debian/*.substvars
debian/cubicweb-doc
debian/cubicweb
debian/files

syntax: regexp
.*/data.*/database/.*
.*/data/ldapdb/.*
.*/data/uicache/
.*/data/libpython/cubicweb_.*/i18n/.*\.po
^doc/html/
^doc/doctrees/
^doc/book/en/devweb/js_api/
^doc/_build
^doc/js_api/
test-results.xml
ve