Retrieve keys from url & id
Add the possibility to retrieve keys from url and from id. Something like:
curl -X POST -d url=http://keydomain.org/key.txt https://nicknym.domain.org:6425 curl -X POST -d id=0x1E34A1828E207901 https://nicknym.domain.org:6425
This is needed to support OpenPGP email header (Feature #3879)
(from redmine: created on 2014-08-04, relates #5919, relates #6018, relates #5400, precedes #5932)