Renamed basic storage module to memory. Implemented persistent storage with nstore.

To choose between the implementations provide an object named persistence in the config object passed to the node constructor.
e.g.
  persistence: {
	type: 'nstore',
	location: 'path/to/nstore.db'
  }

Default type is 'memory', which requires no location parameter.
Merge branch 'ttn' of github.com:garyhodgson/kadoh into ttn