Refactoring:

  * better API/impl isolation
  * better typing system, less opaque/TLV thrown at the user face
  * use the new typed nodes for writing
  * JSON API changed for following the new Java API
Lwm2mServer => LwM2mServer
moved TLV class to impl since it's no more part of the API
added some javadoc, fixed some equals/tostring
typo asyn => async
toString as string format
Rethrow exception thrown during the response visit
enhance project eclipsifiction of mvn eclipse:eclipse
fix some bugs.
use unix line delimiter (\n)
fix: call listeners when a client is updated
Functional & lambda friendly asynchronous API

Split old callback with multip method to functional interface
One consumer for reponse, one for exceptions.