Updated for QGCUASFileManager changes
Added support for progress indication

Also restructured signals to be more command-centric as opposed to
ui-centric.
Added progress indicator, download speed

Also updated to latest QGCUASFileManager implementation.
Merge pull request #818 from DonLakeFlyer/FTPProgressBar

FTP progress bar and download speed
Merge remote-tracking branch 'upstream/master' into joystickinput_settargets