[test] drop dependency on third party cubes
Drop dependency on cubicweb-file, cubicweb-localperms, cubicweb-tag and
cubicweb-comment for cubicweb.test and cubicweb.sobjects.test
Move cubicweb/test/data/libpython/cubicweb_* to cubicweb/test/data, so it's
included in PYTHONPATH.
Add missing parts of schema, entities, views, hooks that make tests pass.
for rtype in ('cw_support', 'cw_dont_cross', 'cw_may_cross'):
drop_relation_type(rtype)
if not 'url' in schema['CWSource'].subjrels:
add_attribute('CWSource', 'url')
add_attribute('CWSource', 'parser')
add_attribute('CWSource', 'latest_retrieval')