Popovers that align to parent now use the window to determine position

Rather than using the bounds of the relative parent to determine whether
or not there is room for a popover to be positioned where intended,
use the full window dimensions.

A limitation to this is the behavior of text line-wrapping, which is
always based on the elements parent.
Merge pull request #9 from lytics/popover-true-offset-bug

Popovers that align to parent now use the window to determine position