Log Message:
Update to 1.19

Upstream changes:
1.19     2018-04-21

- Fix handling of a locale (nds) that does not provide a native name for its
  own locale code. This is a bug in CLDR, but since it exists we should handle
  it sanely.

- If you attempted to thaw a DateTime::Locale::FromData object in a process
  that had not loaded DateTime::Locale this would fail. Reported by Gregor
  Herrmann. GH #18.