LP#1770979: tag item alert type names for translation

LP#1770979: tag item alert type names for translation

This patch tags the stock item alert type names in the seed database
to be translated; it also marks ccat.name as translatable.

This patch intentionally does not include any UI work, as Angularizing
the administration interface for item alert types is a separate bug.

To test
-------
[1] Apply the patch.
[2] Do the following:

    cd build/i18n
    make newpot

[3] Verify that po/db.seed/db.seed.pot includes entries for
    the item alert type names.
[4] (optional) run through the translation process

Signed-off-by: Galen Charlton <gmc@equinoxOLI.org>