[server/test] make unittest_migractions.py use new style cubes MigrationTC used old cube layout in cubicweb/server/test/data-migractions/cubes, move them to new style cubes as "cubicweb_<cubename>" in "apphome" (cubicweb/server/test/data-migractions/) which is added to PYTHONPATH by CubicWebTC.

missing-dep-for-interpreter make => make | build-essential | dpkg-dev (usr/*/cubicweb/skeleton/debian/rules)
embedded-javascript-library usr/share/cubicweb/cubes/shared/data/jquery.js