Move CWSchemaTC to RQLExpressionTC The test actually doesn't require a cubicweb schema, except for testing EmailAdress which is out of scope of the test (testing RQLExpression.transform_has_permission()). Just move the test in existing RQLExpressionTC inheriting from TestCase and rename the tests to be more explicit.

change_attribute_type('CWUser', 'last_login_time', 'TZDatetime')
change_attribute_type('CWSource', 'latest_retrieval', 'TZDatetime')
drop_attribute('CWSource', 'synchronizing')
add_attribute('CWSource', 'in_synchronization')