[tests] Don't import QUnitTestCase into tests' global namespace Unittest's test loader will try to execute QUnitTestCase's test_javascripts method. However this class is intended to be subclassed, not to be executed directly. This change has the following consequences: * slightly faster test execution * almost all rtags warnings are gone

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