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 test over and over again.
installer: Allow host-bin restoration only.