Task #19 Dynamic language

- BPLanguageManager: dynamic localizer
- BPBaseViewController: add notification support for language and
settings changed
- BPUtils: BPLocalizedString macros
- BPDatePicker: localize months
- BPLanguagePicker: select from supported languages
- Localizable.strings: localization strings
- BPSettings: post BPLanguageDidChangeNotification notification for
language setting changed