Buttons &:active and &:focus default styles

[nastiatikk]

Regarding Issue-66 we need to decide if default &:focus and &:active states are something that we want to have for buttons

@ry5n @avelinet @jeffkamo @yourpalsonja @cole-sanderson @mlworks @kpeatt

[jeffkamo]

I agree with Ryan that we don't need :hover. However, I suspect we should still have some form of :active and :focus for a11y reasons, mainly: screen reader user agents.

If we're not sure (which we aren't... at least I'm not 100% sure) then we should test VoiceOver and the Android equivelant.

It also might just be a matter of having at least outline on focus/active, ala http://outlinenone.com/.