raise default version to 1.16.0

this fixes the acceptance tests. But there is a bigger issue here.
The code in manifests/init.pp is not idempotent:
```
 String[1] $nginx_version                                = pick(fact('nginx_version'), '1.6.0'),
```
Turns out on the first run the fact might not be set yet leading to a pre 1.15.0 compatible
configuration on systems wich ship a newer version of nginx. Leading to
```
nginx: [emerg] unknown directive "ssl" in /etc/nginx/sites-enabled/www.puppetlabs.com.conf:25
```

.rspec

@@ -3,3 +3,4 @@
 
 --format documentation
 --color
+--fail-fast

REFERENCE.md

@@ -281,7 +281,7 @@ already installed.  If the fact is unavailable, it defaults to '1.6.0'.
 You may need to set this manually to get a working and idempotent
 configuration.
 
-Default value: `pick(fact('nginx_version'), '1.6.0')`
+Default value: `pick(fact('nginx_version'), '1.16.0')`
 
 ##### <a name="-nginx--debug_connections"></a>`debug_connections`
 

manifests/init.pp

@@ -240,7 +240,7 @@
   Hash $nginx_upstreams                                   = {},
   Nginx::UpstreamDefaults $nginx_upstreams_defaults       = {},
   Boolean $purge_passenger_repo                           = true,
-  String[1] $nginx_version                                = pick(fact('nginx_version'), '1.6.0'),
+  String[1] $nginx_version                                = pick(fact('nginx_version'), '1.16.0'),
 
   ### END Hiera Lookups ###
 ) inherits nginx::params {

spec/acceptance/nginx_mail_spec.rb

@@ -80,7 +80,7 @@ class { 'nginx':
       it { is_expected.to be_listening }
     end
 
-    context 'when configured for nginx 1.14' do
+    context 'when configured for nginx 1.14', if: !%w[Debian Archlinux].include?(fact('os.family')) do
       it 'runs successfully' do
         pp = "
       if fact('os.family') == 'RedHat' {

spec/defines/resource_server_spec.rb

@@ -672,7 +672,7 @@
                 facts[:nginx_version] ? facts.delete(:nginx_version) : facts
               end
 
-              it { is_expected.to contain_concat__fragment("#{title}-ssl-header").with_content(%r{  ssl on;}) }
+              it { is_expected.to contain_concat__fragment("#{title}-ssl-header").with_content(%r{  listen       *:443 ssl;}) }
             end
 
             context 'with fact nginx_version=1.14.1' do