change assets env entry to better namespace

PSGI env entries starting with "psgix." are reserved, so we should be
using our own namespace.

Author: haarg

lib/MetaCPAN/Middleware/Static.pm

@@ -51,7 +51,7 @@ sub wrap {
                 if ($dev_mode) {
                     $assets = $get_assets->();
                 }
-                push @{ $env->{'psgix.assets'} ||= [] }, @$assets;
+                push @{ $env->{'metacpan.assets'} ||= [] }, @$assets;
                 $app->($env);
             };
         };

lib/MetaCPAN/Web/View/Xslate.pm

@@ -74,7 +74,7 @@ around render => sub {
 
     $vars->{api_public}  = $self->api_public;
     $vars->{source_host} = $self->source_host;
-    $vars->{assets}      = $req->env->{'psgix.assets'} || [];
+    $vars->{assets}      = $req->env->{'metacpan.assets'} || [];
     $vars->{current}     = {
         $c->action->reverse    => 1,
         $c->request->uri->path => 1,