tests/12-edit-chroot: Test restoring using crouton -f

Restoring using crouton -f corrupts the output of croutonversion,
as a new croutonversion script is installed, but the installer is
not run, so fields are not updated.
installer: Add TARGETNOINSTALL variable

Tells the target file if it will be installed or not, instead of
repeating the same complicated tests over and over again.
installer: Allow host-bin restoration only.

Add a -b option to the installer that only restores host-bin
scripts, based on the target files installed in all existing
chroots.

Incidentally, this fixes #1106 as crouton -f tarball now only
restores host-bin (and not chroot-bin).
installer: Only expand variables if prepare script is needed
12-edit-chroot: Test host-bin restoration (crouton -b).
Fixes after review.
Fixes after review.
installer: Remove TARGETS='check' hack
installer: Remove useless use of cat
installer: Ensure .crouton-targets is correct

Generate the file in a temp folder, and copy it over when the
installer starts.
installer: run deduptargets on .crouton-targets only
test/12-edit-chroot: Install cli-extra to better test restore bin
Merge pull request #1131 from drinkcat/splittest+edit-chroot-fix

installer: Allow host-bin restoration only.
mkpart.sh: Create a separate partition for crouton.

Prevents accidental wiping when switching between normal and dev modes.
installer, host-bin: Automatically mount crouton partition.
mkpart.sh: Warn if ChrUbuntu is installed. Increase logout timeout.

Thanks @DennisLfromGA for testing
mkpart.sh: Check if chroots are mounted before waiting 10 seconds.

Also readlink /var/run/crouton (on most recent Chromium OS we use
/run/crouton)
We are crouton Authors...

...crunchy and yummy!
mkpart.sh: Use partx instead of partprobe.

partprobe was removed from upstream (crbug.com/377052)
mkpart.sh: Do not run if a Chromium OS update is pending

Fixes #55.