btn-outline.active box shadows

[mudrz]

Bootstrap 4 beta 3

Related to active buttons issue
@ysds
#24760
Related pull request
@mdo
#25070

I agree to remove the focus box shadow from .active.

The focus outline(box shadow) should only be used to highlight the focused elements - only one >element per window has the focus at a time.

In beta 3 the .active box shadow button issue was fixed for regular buttons, but not for outline buttons.
Additionally active outline buttons no longer change their text color when active
https://codepen.io/anon/pen/vpmZZM?editors=1000#0

[719media]

I'm not sure if @mudrz is saying that the btn-outline-* buttons' :active state should have a different text color, but I think he is... and I agree. I think having color: color-yiq($color-hover); on the :active looks "wrong" in that the dark text just seems out of place. It should be a lighter color like the hover (color: color-yiq($color);) IMO.