Request and publication is switched to fully serialised approach, so that
complex data structures like lists and objects can be safely transmitted.

The requests are backward compatible, so for current and simple usage
automatic region is setup.

Much more information are published to main and shared instances, like
lists of available and assigned regions. Regions can be added and removed,
which will be reflected automatically for the slaves.

Information send to the bot node are minimised to only needed ones.

check-frontend-ip-list can be configured according to the list, and each
element overrides previous one:

 * globally on cluster
 * default per region
 * globally per slave
 * specific per region on slave

Note: It's known that:

 {%-     set base_slave_dict = json_module.loads(slave.pop('_')) %} {#- XXX: Unsafe! #}

      is really unsafe, but for most of usage of monitoring slaves it's
      considered good enough.