Adds log to not manage /var/run/redis with systemd

* The existence of /var/run/redis causes the startup of redis-server via
systemd to fail on debian systems with redis-server >= 3.2.8-2:

```
May 18 19:17:54 debian-8 systemd[1]: Starting Advanced key-value store...
       May 18 19:17:54 debian-8 systemd[803]: Failed at step RUNTIME_DIRECTORY spawning /bin/run-parts: File exists
       May 18 19:17:54 debian-8 systemd[804]: Failed at step RUNTIME_DIRECTORY spawning /usr/bin/redis-server: File exists
       May 18 19:17:54 debian-8 systemd[1]: redis-server.service: control process exited, code=exited status=233
       May 18 19:17:54 debian-8 systemd[1]: Failed to start Advanced key-value store.
       May 18 19:17:54 debian-8 systemd[1]: Unit redis-server.service entered failed state.
       May 18 19:17:54 debian-8 systemd[1]: redis-server.service holdoff time over, scheduling restart.
```
* It will actually eventually start, but the first run will fail
* The default unit file for redis-server in debian jessie-backports
contains `RuntimeDirectory=redis`, see [this commit](https://github.com/lamby/pkg-redis/commit/1cecea5abcb2ce05beacd4347977634d06c59cef).
* Adds logic to not manage the /var/run/redis directory if systemd present

manifests/config.pp

@@ -135,20 +135,24 @@
         owner  => $::redis::config_owner,
       }
 
-      case $::operatingsystem {
-        'Debian': {
-          $var_run_redis_mode = '2775'
-        }
-        default: {
-          $var_run_redis_mode = '0755'
+      $service_provider_lookup = pick(getvar_emptystring('service_provider'), false)
+
+      if $service_provider_lookup != 'systemd' {
+        case $::operatingsystem {
+          'Debian': {
+            $var_run_redis_mode = '2775'
+          }
+          default: {
+            $var_run_redis_mode = '0755'
+          }
         }
-      }
 
-      file { '/var/run/redis':
-        ensure => 'directory',
-        owner  => $::redis::config_owner,
-        group  => $::redis::config_group,
-        mode   => $var_run_redis_mode,
+        file { '/var/run/redis':
+          ensure => 'directory',
+          owner  => $::redis::config_owner,
+          group  => $::redis::config_group,
+          mode   => $var_run_redis_mode,
+        }
       }
 
     }

spec/acceptance/redis_debian_run_dir_spec.rb

@@ -0,0 +1,53 @@
+require 'spec_helper_acceptance'
+
+describe 'redis', :if => (fact('operatingsystem') == 'Debian') do
+  it 'should run with newer Debian package' do
+    pp = <<-EOS
+
+    include ::apt
+
+    class {'::apt::backports':}
+    ->
+    file { '/usr/sbin/policy-rc.d':
+      ensure  => present,
+      content => "/usr/bin/env sh\nexit 101",
+      mode    => '0755',
+    }
+    ->
+    package { 'redis-server':
+      ensure => 'latest',
+      install_options => {
+        '-t' => "${::lsbdistcodename}-backports",
+      },
+    }
+    ->
+    class { 'redis':
+      manage_package => false,
+    }
+    EOS
+
+    apply_manifest(pp, :catch_failures => true)
+    apply_manifest(pp, :catch_change   => true)
+  end
+
+  describe package('redis-server') do
+    it { should be_installed }
+  end
+
+  describe service('redis-server') do
+    it { should be_running }
+  end
+
+  context 'redis should respond to ping command' do
+    describe command('redis-cli ping') do
+      its(:stdout) { should match /PONG/ }
+    end
+  end
+
+  context 'redis log should be clean' do
+    describe command('journalctl --no-pager') do
+      its(:stdout) { should_not match /Failed at step RUNTIME_DIRECTORY/ }
+    end
+  end
+
+end