Python: combined old and new functionality of elliptics.Node.add_remote. Now remote can be added by follow ways:
  * node.add_remote(host:port:family)
  * node.add_remote(host, port)
  * node.add_remote(host, port, family)
  * node.add_remote(elliptics.Address)
  * node.add_remote([ host:port:family, elliptics.Address])
Pytests: added tests for node: adding remotes in different manners.