fixed detect a unifile service thx to isLoggedIn since this attribute…

… is never set by unifile (my PR has never been merged)

src/js/UnifileService.js

@@ -299,6 +299,7 @@ export default class UnifileService {
   }
 
   static isService (file) {
-    return typeof file.isLoggedIn !== 'undefined';
+    console.log('isService', file, file.isLoggedIn);
+    return typeof file.mime === 'application/json';
   }
 }