Add marker needs_ipaapi and option to skip tests

The new marker needs_ipaapi is used to mark tests that needs an
initialized API (ipalib.api) or some sort of other API services (running
LDAP server) to work. Some packages use api.Command or api.Backend on
module level. They are not marked but rather skipped entirely.

A new option ``skip-ipaapi`` is added to skip all API based tests. With
the option, only simple unit tests are executed. As of now, freeIPA
contains more than 500 unit tests that can be executed in about 5
seconds.

Signed-off-by: Christian Heimes <cheimes@redhat.com>
Reviewed-By: Alexander Bokovoy <abokovoy@redhat.com>

ipatests/test_ipapython/test_session_storage.py

@@ -11,6 +11,7 @@ from ipapython import session_storage
 
 
 @pytest.mark.skip_ipaclient_unittest
+@pytest.mark.needs_ipaapi
 class test_session_storage(object):
     """
     Test the session storage interface