Add in migration from old style v1 rest uris to new style, e.g.
key@http://url.com -> http://key@url.com

Tested:
  Unit.
Merge pull request #100 from nightscout/tr.resturitranslate

Add in migration from old style v1 rest uris to new style, e.g.
Clean up the settings activity. Because we are targeting sdk > 11, we
can remove a lot of cruft.

Add some preference validation. Add tests for validation. Note: this
only validates uri syntax, not if the hosts actual exist. That will come
later as a button (or something).

Tested:
  ./gradew clean test