Update beaker setup for xenial

Add a xenial nodeset and update the spec helper to install puppet 3 from
the Ubuntu repos instead of from puppetlabs.

Change-Id: I46395c93b83e3a9234ca3023830c74eefc68c925

spec/acceptance/nodesets/nodepool-xenial.yml

@@ -0,0 +1,10 @@
+HOSTS:
+  ubuntu-16.04-amd64:
+    roles:
+      - master
+    platform: ubuntu-16.04-amd64
+    hypervisor: none
+    ip: 127.0.0.1
+CONFIG:
+  type: foss
+  set_env: false

spec/spec_helper_acceptance.rb

@@ -1,7 +1,15 @@
 require 'beaker-rspec'
 
 hosts.each do |host|
-  install_puppet
+  # puppet 3 isn't available from apt.puppetlabs.com so install it from the Xenial repos
+  on host, "which apt-get && apt-get install puppet -y", { :acceptable_exit_codes => [0,1] }
+  # otherwise use the beaker helpers to install the yum.puppetlabs.com repo and puppet
+  r = on host, "which yum",  { :acceptable_exit_codes => [0,1] }
+  if r.exit_code == 0
+    install_puppet
+  end
+  add_platform_foss_defaults(host, 'unix')
+
   on host, "mkdir -p #{host['distmoduledir']}"
 end