OX: Announce public key on PEP

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

Makefile.am

@@ -18,6 +18,7 @@ core_sources = \
 	src/xmpp/blocking.c src/xmpp/blocking.h \
 	src/xmpp/form.c src/xmpp/form.h \
 	src/xmpp/avatar.c src/xmpp/avatar.h \
+	src/xmpp/ox.c src/xmpp/ox.h \
 	src/event/common.c src/event/common.h \
 	src/event/server_events.c src/event/server_events.h \
 	src/event/client_events.c src/event/client_events.h \