Use a new ruby 2.1 in the master node as a single ruby version.

* setup supervisor to use system ruby instead of rbenv ruby;
* code is given in accordance with Ruby 1.9 or higher;
* remove symbolic link to astute bin agent.

Implements: blueprint fuel-new-system-ruby-in-master-node
Change-Id: I41d23330443b592d045186dc989df9e4dc72d387