MainWorkflow: Fix wrong uuid given by libraryClipInfo

I don't know why this happend... So shameful

src/Gui/timeline/Track.qml

@@ -169,7 +169,7 @@ Item {
                     }
                     else {
                         var newClipInfo = workflow.libraryClipInfo( drag.getDataAsString( "vlmc/uuid" ) );
-                        currentUuid = "" + newClipInfo["libraryUuid"];
+                        currentUuid = "" + newClipInfo["uuid"];
                         newClipInfo["position"] = ptof( drag.x );
                         if ( newClipInfo["audio"] ) {
                             newClipInfo["uuid"] = "audioUuid";

src/Workflow/MainWorkflow.cpp

@@ -241,7 +241,7 @@ MainWorkflow::libraryClipInfo( const QString& uuid )
     h["video"] = c->media()->hasVideoTracks();
     h["begin"] = c->begin();
     h["end"] = c->end();
-    h["uuid"] = "libraryUuid";
+    h["uuid"] = c->uuid().toString();
     return QJsonObject::fromVariantHash( h );
 }