A fix for ESPRESSO-8 and ESPRESSO-9.

Use approach we have used already to theme status bar
and Power Off dialog. This time we are theming all
alert dialogs. Strictly speaking, the change is only
necessary if an alert dialog includes a list view.

NP: Most likely this change will be backed out after
we figure out how to properly modify system context's
asset manager.

CR:JoshG.