src/pgp/gpg.c:p_ox_gpg_readkey
Used to read a public key from a file. The function will return the fingerprint
of the file and the base64 encoded key.
src/xmpp/ox.[hc]
ox_announce_public_key(const char* const filename) can be called from the /ox
announce <filename> command. The key within the file will be pushed on PEP and
the Metadata node will be set.
Issue: #1331
