[installer] [host]
add device selection:
	device selection widget
	NixDiskDevice for OSX and Linux disk handling
	io.cpp: add enumeration routines for OSX and Linux
add download widget to show progress when downloading the disk image.
add license agreement widget
add a success dialog widget for when installation is complete
remove ui_ include references in MainWindow
fix #ifdefs with ||
add rotateWidget method to rotate QWidget display
fix a race condition, where the mirror redirect URL is not resolved before we try to see what builds are available by moving language selection and version selection to slot and adding a spinner