Amend copyright disclaimer, licence and clarify ustyle

[annez]

Currently our copyright is "uSwitch limited". We should be considering amending this to also include our parent company ZPG.

Clarifying ustyle

As we are wanting to use http://ustyle.guide/brand/logo.html as our absolute guidelines, we should clarify what ustyle is, what it is used for and that it is the de-facto place for uSwitch ltd. brand guidelines. The idea here is to redirect this: https://www.uswitch.com/media-centre/resources/ to ustyle.guide and let that be our only place for branding resources.