Debugging

* Changed UI
* Improved USB recognition
* Improved progress indication
* Minor code changes
Check if device is in use

* Check if device is in use before cleaning the USB
* Adapted readme.txt
Check if device is in use

* Check if device is in use before cleaning the USB
* Adapted readme.txt
Merge pull request #2 from SolydXK/schoeljes_general_debugging

Debugging