Behaves similarly to the DatabaseUpgradeActivity. You have a
static list of ExperienceUpgrade models that include a "trigger"
version, where when a user upgrades through it a notification
will appear, and there will be a splash explanation screen.
Right now the splash screens are basic and not too configurable,
but that can be reworked as upgrades demand.
Closes#4151
1) fixed DateUtils to use SimpleDateFormat for everything because it respects Locale
2) added getCurrentLocale() method to DynamicLanguage
3) allow PassphraseRequiredActionBarActivity.initFragment() to accept a Locale
4) updated classes that depend on DateUtils to pass down Locale from DynamicLanguage
Fixes#2684Closes#2725
// FREEBIE
