feat(80usrgptprio): initial commit
fix(80usrgptprio): Convert test case to same spacing as module code.

Consistency ftw!
fix(80usrgptprio): Do not run without usr=gptprio
fix(80usrgptprio): Fix fail-everything test case.
fix(80usrgptprio): Fix backup/setup of symlinks root filesystem.

Don't bother backing up /usr, as long as it is a directory we can just
mount on top of it and no data will be lost, just kinda hidden.
Shouldn't happen much.

Never delete anything, just work harder to find a safe backup name.

Don't backup/create symlinks that are already correct.
fix(80usrgptprio): Fix fail-kernel test case.
fix(80usrgptprio): Fix kexec-fail test case.
fix(80usrgptprio): Fix mount-fail test case.
fix(80usrgptprio): Fix normal test case. Enable 80usrgptprio testing.
fix(80usrgptprio): Support kernels in both /usr/boot and /boot

/usr/boot has priority but fall back to the current location in /boot.
This is only required temporarily for testing.
fix(80usrgptprio): Update usr= option, not root=
fix(80usrgptprio): Add basic support for plain block devices

Need to turn the usr= kernel parameter into a fstab entry so the normal
mount process will mount it. Now boot gets all the way past pivot_root!
Merge pull request #19 from marineam/move-usr

gptprio module for /usr