Prevent feedrate increase popup from opening multiple times

The popup to show that the max feed rate has been increased would open ever time Ground Control was opened until another setting was changed...this PR foreces a write to disk so that it will only show once

Author: BarbourSmith

main.py

@@ -107,6 +107,7 @@ def build(self):
         if self.config.get('Advanced Settings', 'maxFeedrate') == '700':
             self.data.message_queue.put("Message: This update will increase the maximum feedrate of your machine. You can adjust this value under the Advanced settings.")
             self.config.set('Advanced Settings', 'maxFeedrate', '800')
+            self.config.write()
 
         self.data.comport = self.config.get('Maslow Settings', 'COMport')
         self.data.gcodeFile = self.config.get('Maslow Settings', 'openFile')