Improve the creation of nodes and move all to the main khashmir class.

Improve the creation of nodes and move all to the main khashmir class.

Nodes are now initialized with their id, host and port
(optionally stored in a dict) instead of needing 2 steps.

All other classes now call the main khashmir Node() constructor
which adds the udp connection and table.

Previous actions that called insertNode on the table now
call it on the main khashmir class, so that if buckets are
full they can have a chance of being added.