Add to ingore aria- generated attrs

In BEMHTML and BH these attributes also automatically generate (by timestamp):
http://www.w3.org/WAI/PF/aria/states_and_properties#aria-labelledby
http://www.w3.org/WAI/PF/aria/states_and_properties#aria-describedby
As generation time is different from each generation process, we need to ignore these attributes.