try to index media immediately on import

Since indexing is supplemental, it can be made a background task that can occur
at more or less any time. So we run it as soon as possible.

app/project/projectsavemanager.cpp

@@ -32,5 +32,5 @@ void ProjectSaveManager::Action()
     project_file.close();
   }
 
-  emit Finished();
+  emit Succeeeded();
 }