Rather than our custom class, we can get pretty far using existing UISearchBar
styling, and then apply the final tweak, the search bar text field background
color by traversing the view.
This fixes a couple issues:
1. There was a small wavering in height of the custom search bar
2. When your table header view is a UISearchBar you get nice scroll "snapping"
when showing/hiding the search bar.
75bb9b60db