Adopt CSP plugin for main headers

Change-Id: I1d08860622091a5806172deafad9e819114fc078
diff --git a/lib/Kalamar.pm b/lib/Kalamar.pm
index 9ec798e..b13de68 100644
--- a/lib/Kalamar.pm
+++ b/lib/Kalamar.pm
@@ -119,22 +119,6 @@
     );
   };
 
-  my $csp = $conf->{cs_policy} // (
-    "default-src 'self';".
-      "style-src 'self' 'unsafe-inline';".
-      "frame-src *;".
-      "media-src 'none';".
-      "object-src 'self';".
-      "font-src 'self';".
-      "img-src 'self' data:;"
-    );
-
-  $self->hook(
-    before_render => sub {
-      shift->res->headers->header('Content-Security-Policy' => $csp);
-    }
-  );
-
   # API is not yet set - define the default Kustvakt api endpoint
   $conf->{api_path} //= $ENV{KALAMAR_API} || 'https://korap.ids-mannheim.de/api/';
   $conf->{api_version} //= $API_VERSION;
@@ -159,6 +143,17 @@
     HTML => 1
   });
 
+  # Establish content security policy
+  $self->plugin(CSP => {
+    'default-src' => 'self',
+    'style-src' => ['self','unsafe-inline'],
+    'frame-src' => '*',
+    'media-src' => 'none',
+    'object-src' => 'self',
+    'font-src' => 'self',
+    'img-src' => ['self', 'data:']
+  });
+
   # Localization framework
   $self->plugin(Localize => {
     dict => {