Refactored popUpView layout and animation

Brought in changes from ‘ASProgressPopUpView’. When animating the
slider the shape of the popUpView now animates also.
Call 'layoutIfNeeded' at end to reduce layout passes

Setting ‘minimumTrackTintColor’ causes a layout pass. Therefore,
placing [self layoutIfNeeded]; after setting track tint coalesces the
layout updates into one.
Optional animation when showing/hiding popUpView
Minor adjustment to animation timing
Merge branch 'anim_fix' into popup_refactor
Release 0.9.4
Merge branch 'popup_refactor'