Restore non-commercial Offer descriptions

Release 1.0f added non-commercial Offer descriptions (per
http://lists.w3.org/Archives/Public/public-vocabs/2014Feb/0028.html)
that accidentally regressed and were fixed in early April
(http://lists.w3.org/Archives/Public/public-vocabs/2014Apr/0093.html).

This fixes the most recent regression (hopefully forever!) :)

Signed-off-by: Dan Scott <dan@coffeecode.net>
Merge pull request #9 from dbs/non-commercial-offer

Restore non-commercial Offer descriptions