Use full naming for `aCallback`

Applies to #264 and https://github.com/Martii/OpenUserJS.org/commit/d7465a3d390d56693ce309aff80ee5bdbfe4df89#commitcomment-7004333

> You don't use short forms (cb = callback) with verbose varible name standards.

Not explicitly declared the STYLEGUIDE** but can be used to accomodate those who don't know what the short term of a callback is... been debating on making a minimum length too. e.g. not one letter identfiers with a potential prefix.