Update once.js

[rafgeekee]

Updated onceClass to allow for a mixed (Array and Map) syntax as per the ngClass docs:

once-class="[style4, {orange: warning}]"

i'm aware its not perfect and needs refactoring, however it is a starting point to add the behaviour.

refer to https://docs.angularjs.org/api/ng/directive/ngClass for the angular doc on ngClass.