Fixes for page history and language selector crashes.

Recent changes to "showAlert" to make it work with modally
presented views was causing crashes with non UIViewController
storyboard elements. This happened because showAlert is
adding its view to whatever view controller invokes it
(at most once) and UITableViewControllers don't play nice
with autolayout if you try to add an autolayout constrained
view to their view. Super lame. Quick fix was to simply
use UIViewControllers in the storyboard (which then
contain the UITableViews as subviews).

Fixed bug with article language selection not using
MWPageTitle.

Updated page history date heading background colors to match
chrome color.

Change-Id: I9fad5d8ff75aeedd089bc8d9f0272ff4cfa9529d