TT#134102 API language handling

* Fix for language solving for API requests. Changed the sequence of language choosing:
1. Request parameter "lang" for API and UI.
2. Cookie value "ngcp_panel_lang" for UI only.
3. User agent/browser language for API and UI.

Change-Id: Id5d814deead22eb7e2908fdc742b0c8474314d49

lib/NGCP/Panel/Controller/Root.pm

@@ -58,11 +58,9 @@ sub auto :Private {
         }
         # clear form cache (they need to be properly re-translated)
         NGCP::Panel::Form::clear_form_cache();
-    }
-    unless ($is_api_request) {
-        if (defined $c->session->{lang}) {
+    } elsif (defined $c->session->{lang}) {
         $c->languages([$c->session->{lang}, "i-default"]);
-        } elsif ( $c->req->cookie('ngcp_panel_lang') ) {
+    } elsif ( ! $is_api_request && $c->req->cookie('ngcp_panel_lang') ) {
         $c->session->{lang} = $c->req->cookie('ngcp_panel_lang')->value;
         $c->languages([$c->session->{lang}, 'i-default']);
     } else { # if language has not yet be set, set it from config or browser
@@ -71,10 +69,10 @@ sub auto :Private {
             $c->languages([$c->config->{appearance}{force_language}, 'i-default']);
         } else {
             $c->languages([ map { s/^en.*$/i-default/r } @{ $c->languages } ]);
+            $c->log->debug("lang set by browser: " . $c->language);
         }
-            $c->session->{lang} = $c->language;
-            $c->log->debug("lang set by browser or config: " . $c->language);
-        }
+        $c->session->{lang} = $c->language
+            if ! $is_api_request;
     }
 
     ################################################### timezone retrieval