Make config accessible through file/GUI for compiled version

[kmeesters]

Currently the config file is embedded in the exe (windows) this should be separated. Additionally, some config options should be accessible through the GUI (like mhub server and node)

[rikkertkoppes]

We may be able to

• use the embedded config as the defaults
• save a file on disk with nodejs that is a copy of that default
• open an api to save stuff to that file
• have the config window write to that api