Bug 1062269 - Load JSON file with shared function in the WhiteList obj

Replace the code for loading a JSON file in the WhiteList object with the new shared function
This won't work because the code below uses the first and second returned values coming from the wpm_getApp() and wpm_getConfig() promises. Putting WhiteList.init() at the begging of the list breaks this but you didn't catch the issue in testing because we need to add an init() method to the MockWhiteList mock that exposes the issue. Putting WhiteList.init() as the last element in the array should suffice.