[cwvreg] load registry using modules names instead of directories Introspect cubicweb, cubes and apphome using pkgutil to generate the full list of modules names for loading registries. Avoiding using bogus logilab.common.modutils.modpath_from_file().

addressbook
basket
blog
book
calendar
comment
company
email
file
folder
i18ncontent
keyword
link
mailinglist
person
tag
timeseries
vcsfile