Change to GTKSpinButton

* Changed to GTKSpinButton and got rid of the error-message label because the SpinButton handles the limitations
* Some settings could be done in the ui, some I had to do in the code
* It will only update when focussing out
* When the set port can't be used (eg port is already in use), another will be chosen (this was existing logic)
1 job for Allow_to_change_port_on_webremote_plugin in 12 minutes and 17 seconds (queued for 1 second)
Status Job ID Name Coverage
passed test #1305232