GCS/ScrollDecorator.qml deleted destructor

avoids qrc:/welcome/qml/ScrollDecorator.qml:21: TypeError: Cannot read
property of null message
GCS/Uploader only close usb port on exit if open

avoids pjrc_rawhid_unix: Invalid device number used (0) message
Merge pull request #1296 from guilhermito/gcs_closing_warnings

Gcs closing warnings fix