* Rework the whole imaging process for writing to devices: - Use an equivalent of dd to make an exact copy of the image to the device - This also breaks persistence. * Update UI and frontend code to drop the persistence widgets. * Drop Erase Disk widgets too. * debian/usb-creator-common.postinst, debian/usb-creator-common.prerm: stop usb-creator-helper on package upgrades and removals. (LP: #1497569)