Fixes for page history and language selector crashes.

Recent changes to "showAlert" to make it work with modally
presented views were causing crashes with non UIViewController
storyboard elements. This happened because showAlert is
adding its view to whatever view controller invokes it but
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