Implement "Country Required" blueprint

[Paul Everitt]

Implement the blueprint at:

  https://blueprints.launchpad.net/karl3/+spec/country-required

Read the "Status Whiteboard" about the specification, particularly the note about GSA.

[Tres Seaver (tseaver)]

I believe we can change the add / edit forms for profiles to make this
field required, without worrying about GSA-side input, as long as we
don't make any other view depend strongly on the field's non-emptiness.

[Tres Seaver (tseaver)]

Changes implementing this blueprint are now checked in on the branches
named 'tseaver-require_profile_country' (one each for the buildout and
the 'src/karl' package.

These changes should be ready for merge at the start of the M48 integration
cycle.

[JimPGlenn (jpglenn09)]

released