Portable & update notification

[kevincentius]

• [x] App name should make it clear that the app is portable - no installations / footprint (although maybe appdata or something?)
• [x] Main server provides the version number of the currently supported client version
• [x] Client checks if the version number matches at start up. If it doesn't match, show a dialog with the download link for the latest version (just google drive?)
• [ ] Save version notification flag - if a new version is opened for the first time, show a short update log

[kevincentius]

update log not needed yet I guess, maybe later when we have more testers