R1:4f2aa992483a

Add "serviceName" and "serviceType" to bot and chat logger

Summary:
Make each adapter provide a "serviceType" (campfire, flowdock, IRC) and "serviceName" (irc network / chat server) so that we can disambiguate between, e.g., "#phabricator on EFNet" and "#phabricator on FreeNode".

Make the chatlog handler ship them over Conduit.

Also fix some "policy can not be null" bugs with chatlog recording.

Test Plan:
Verified data inserted correctly:

mysql> select * from chatlog_channel;
+----+…