Log Message:
Update chat/ejabberd to 15.04. Add sqlite option.

Upstream changes:
- R16B03-1 is now the minimal required Erlang/OTP version
- SQLite support
- Default db_type can be specified with global default_db option
- Included mod_muc_admin, mod_admin_extra and mod_multicast modules
- Removed ejabberd_http_poll
- Pubsub improvements
- Better RFC compliance
- Several other bugfixes