Preparation for scenario_node_terminus tests

Initial preparation:
* Adapt the README with instructions to download and prepare SNT
* Install SNT into the vagrant instances used in the system tests
* all the necessary plumbing around the above two tasks

Change-Id: Ibc9d60f54061d7dbb6e19520597154a06f70382a

Puppetfile

@@ -11,3 +11,6 @@ mod 'puppetlabs/apt',
 mod 'puppetlabs/inifile',
   :git => 'git://github.com/puppetlabs/puppetlabs-inifile',
   :ref => '1.0.3'
+
+mod 'bodepd/scenario_node_terminus',
+  :git => 'git://github.com/bodepd/scenario_node_terminus'

README.md

@@ -79,6 +79,7 @@ and tests are in spec/system. It runs virtual machines and requires
 * BUNDLE_PATH=/tmp/vendor bundle install
 * BUNDLE_PATH=/tmp/vendor bundle exec rake lint
 * BUNDLE_PATH=/tmp/vendor bundle exec rake spec
+* git clone https://github.com/bodepd/scenario_node_terminus.git ../scenario_node_terminus
 * BUNDLE_PATH=/tmp/vendor bundle exec rake spec:system
 
 The RELEASES environment variable contains the list of ceph releases

spec/spec_helper_system.rb

@@ -38,6 +38,9 @@ RSpec.configure do |c|
       puppet_module_install(:source => proj_root,
                             :module_name => 'ceph',
                             :node => vm)
+      puppet_module_install(:source => File.join(proj_root, '../scenario_node_terminus'),
+                            :module_name => 'scenario_node_terminus',
+                            :node => vm)
       shell(:command => 'puppet module install --version 4.1.0 puppetlabs/stdlib',
             :node => vm)
       shell(:command => 'puppet module install --version 1.0.0 puppetlabs/inifile',