gossip: Refactor initialisation of callback modules to use proplists
gossip_load: Implement initialisation with proplists
gossip: move range calculation from dht_node_join to gossip

Move the calculation of the range (from the neighborhood) at startup from
dht_node_join to gossip.
gossip: Add neighbors to the init proplist of callback modules
gossip_cyclon: add initialization
gossip_cyclon: implement select_data
gossip_cyclon: implement get_node_details_response
wip