Fix more Dialyzer warnings
Allow multiple entry with same nick to MUC rooms (thanks to Magnus Henoch)(EJAB-305)
Explicitly skip useless ejabberd 2.0* mnesia tables when restoring backup

Reference:
http://www.ejabberd.im/node/4867
enable pubsub#deliver_notification checking (thanks to Karim Gemayel)(EJAB-1453)
Updated mysql schema with current dump (EJAB-1474)
Use the syntax PRIMARY KEY (field(int)) only for MySQL (EJAB-1337)
Fix zlib compression connection (EJAB-1448)
Replace the full ejabberd_zlib into a simple exmpp_compress interface (EJAB-991)
Replace calls of OTP's Binary, since they would require R14
Fix SCRAM auth of uppercase passwords (EJAB-1196)
Fix SASL auth error conditions
Fix support to negotiate zlib compression after starttls
Fix typo in the Guide about user_regexp
Fix SCRAM to support attributes which value has only one character
Clarification about system user of ejabberd.init
Support to import XML files without password-format attribute
Improve room config change logging, due to allow_private_messages_from_visitors
Fixed support for multi-resource occupants (EJAB-305)
Avoid crash when performing admin action (thanks to Evgeniy Khramtsov)
No need to explicitly skip old useless tables, simply fix keep_tables