HashManager reset

We've applied the Sky toolkit to articles on the main help site (http://help.sky.com) as part of an update to make them responsive. This site is a single-page app, so to ensure that tabs within articles can be initialised (or reinitialised) correctly after navigation we needed to add and expose a method to reset the globalHashList object. This method is self-contained and shouldn't impact any existing implementations of the toolkit.