ENYO-468: Date and Time pickers now properly handle `null` locale setting.

The sample has also been improved to be more reliable during initialization, resetting the locale at create-time.
There is technically some duplication of code here, but the change to DateTimePicker is to include this `null` or `0` or `undefined` locale setting to reset to "local" locale. The sample, at initialization time, is already set to undefined/null, which doesn't trigger the localeChanged method, thereby not calling an ilib locale change.

Enyo-DCO-1.1-Signed-off-by: Blake Stephens <blake.stephens@lge.com>