cleanup origin URL detection and progress bar stuff

WebViewTab progress was getting clobbered among other tabs, so a
background tab loading something would show a progress bar when it
wasn't the current tab.
make it clear what UILaunchStoryboardName is referencing
sadly, UIKeyboardTypeURL can't be used in our URL field

We're also searching here, and UIKeyboardTypeURL takes away our
space bar.  Use UIKeyboardTypeSearch to get it back.
evolve CookieWhitelistController to also allow viewing/deleting per-domain cookies