Add test for puppet implementation

In OpenVoxProject/openvox-agent#66 someone
reported issues during `puppet lookup` with the changes from
#63 or
#78.

It's also easy to reproduce it locally:

```
root@:~# puppet lookup puppet::puppetmaster
Warning: The node parameter 'implementation' for node 'mirror.voxpupu.li' was already set to 'openvox'. It could not be set to 'openvox'
--- voxpupu.li
root@:~# echo $?
0
root@:~#
```

Author: bastelfreak

acceptance/tests/lookup/issue_66_implementation.rb

@@ -0,0 +1,57 @@
+# test for https://github.com/OpenVoxProject/openvox-agent/issues/66
+test_name 'Warning about implementatin during puppet lookup' do
+  require 'puppet/acceptance/puppet_type_test_tools.rb'
+  extend Puppet::Acceptance::PuppetTypeTestTools
+
+# bastelfreak: I've no idea what those tags do, I copied them from lookup/v4_hieradata_with_v5_configs.rb
+tag 'audit:high',
+    'audit:acceptance',
+    'audit:refactor',  # Master is not needed for this test. Refactor
+                       # to use puppet apply with a local module tree.
+
+  app_type        = File.basename(__FILE__, '.*')
+  tmp_environment = mk_tmp_environment_with_teardown(master, app_type)
+  fq_tmp_environmentpath  = "#{environmentpath}/#{tmp_environment}"
+
+  confdir = puppet_config(master, 'confdir', section: 'master')
+  hiera_conf_backup = master.tmpfile('66-hiera-yaml')
+
+  step "backup global hiera.yaml" do
+    on(master, "cp -a #{confdir}/hiera.yaml #{hiera_conf_backup}", :acceptable_exit_codes => [0,1])
+  end
+
+  teardown do
+    step "restore global hiera.yaml" do
+      on(master, "mv #{hiera_conf_backup} #{confdir}/hiera.yaml", :acceptable_exit_codes => [0,1])
+    end
+
+    agents.each do |agent|
+      on(agent, puppet('config print lastrunfile')) do |command_result|
+        agent.rm_rf(command_result.stdout)
+      end
+    end
+  end
+
+  step "create global hiera.yaml and data" do
+    create_remote_file(master, "#{confdir}/hiera.yaml", <<-HIERA)
+---
+version: 5
+hierarchy:
+  - name: common
+    data_hash: yaml_data
+    path: "common.yaml"
+    HIERA
+    on(master, "chmod 755 #{confdir}/hiera.yaml")
+    create_remote_file(master, "#{confdir}/common.yaml", <<-YAML)
+---
+environment_key: environment_key-global_common_file
+global_key: global_key-global_common_file
+    YAML
+  end
+
+  step 'assert lookups using lookup subcommand' do
+    on(master, puppet('lookup', 'environment_key'), :accept_all_exit_codes => true) do |result|
+      assert_match(/Warning: The node parameter 'implementation' for node '.*' was already set to 'openvox'. It could not be set to 'openvox'/, result.stderr)
+    end
+  end
+end