Fix push resinfo for app resources

The patch introducing is_string() in replacement of type() == str
was bogus, causing the following error on push resinfo:

list index out of range ['Error', 'info not implemented in launcher']

lib/resApp.py

@@ -237,7 +237,7 @@ def info(self):
             return self.fmt_info(keyvals)
         self.validate_on_action()
         buff = self.run('info', dedicated_log=False, return_out=True)
-        if is_string(buff) != str or len(buff) == 0:
+        if not is_string(buff) or len(buff) == 0:
             keyvals.append(["Error", "info not implemented in launcher"])
             return keyvals
         for line in buff.splitlines():