Alternatives

Fix compatibility with ansible 1.6.7 and above.

Since ansible 1.6.7 it is no longer allowed to insert parameters in module args (check
https://groups.google.com/forum/#!topic/ansible-announce/RGEEMmFaqBQ
and CVE-2014-4967) As such, the tasks for adding node to the PATH
and the update-alternatives execution had to be changed.
Also, the alternatives modules is now used for executing the
update-alternatives.