[web/ajax] don't override any status code with 500 in ajax_error_handler
If the request produced an error such as Unauthorized or NotFound,
core_handle sets an appropriate status_out. Which is then overridden by
the ajax error handler.
change_attribute_type('CWCache', 'timestamp', 'TZDatetime')
change_attribute_type('CWUser', 'last_login_time', 'TZDatetime')
change_attribute_type('CWSource', 'latest_retrieval', 'TZDatetime')
drop_attribute('CWSource', 'synchronizing')
add_attribute('CWSource', 'in_synchronization')