[devtools] Simplify test configuration's init Specify module's __file__ instead of apphome. __file__ is saved on the class as it will be used later (eg to find the proper pg cluster without relying on shared dictionnary modifications). This will require some tests update, but it should be less common in cubes than in cubicweb itself.

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