[installer] [host] use gksudo instead of sudo. My assumption of sudo working would require NOPASSWD in /etc/sudoers. Use gksudo instead.
[installer] [host] thanks labsin: make sure we truly quit if we can't unmount before imaging
[installer] [host] cosmetic cleanup: tidy up comments. Logging: write to log in OSX IO routines instead of qDebug(); IO: include "nixdiskdevice.h" in OSX and Linux headers, rather than in io.h. This means Windows will build properly
[installer] [host] thanks srm: add a back button
[installer] [host] stubs for writing to linux and unmounting linux disks
[installer] [host] on Linux, inform OS of changes to partition table before we do anything
[installer] [host] linux: only try and unmount mounted partitions on the disk. Unlike OSX there is no way of unmounting an entire disk, so we check /proc/mounts instead.
[installer] [host] OSX: cosmetic and fix for returning true when image fails