Ignore po backup files (po~)

MVC4 Demo:
Add view model with translatable annotations
Display model in view
Add action to set language in session
Add test strings in pl (polish) translation file
Add web config to locale folder so its not externally accessible
Add translatable string in views, models and controllers
set base view page for razor views to be I18NWebViewPage
Added generated po files
use I18nModelMetadataProvider
Disable automatic routing (pending a fix)
Fix LocalizingService.GetTextOrDefault so that it doesnt crash if localizable annotation property is null.

Add extra comments and tidy I18nModelMetadataProvider.