merge issue/58 branch to upstream master tree

[acoul]

this commit concerns issue #58

[coveralls]

Coverage remained the same at 100.0% when pulling bc10c14 on acoul:master into 9b2be9c on netjson:master.

[nemesifier]

Hey @acoul, thanks for contributing! Is this #62 or did you change something and if yes what?
Next time, if you can, try to leave my commit untouched and add your changes to a new commit, that way I can review it more easily.

[acoul]

Hi @nemesisdesign. yes this is about #62. No code changes from your initial commit. just adjusting your code to the recent master tree changes. Will try to follow your suggestion on my next pull request.

As you can see, there are no orphan nodes anymore: http://nmsbgp.ozo.com/topology/0d55efe8-6219-49e9-9435-6c0c5b438ea7/