Bug 6684: Fixes to koha-remove

Bug 6684: Fixes to koha-remove

Fixes bugs 6684 6997 4880:
6684 koha-remove should check the number of arguments it gets
6997 koha-remove leaves system in inconsistent state if there is an error
4880 koha-remove sometimes fails because user is logged in

Amended by chrisc@catalyst.net.nz
Trying to resolve conflicts.

Signed-off-by: Jared Camins-Esakov <jcamins@cpbibliography.com>
Rebased on top of bug 7924.

Signed-off-by: Paul Poulain <paul.poulain@biblibre.com>
Signed-off-by: Chris Cormack <chrisc@catalyst.net.nz>
Signed-off-by: Jared Camins-Esakov <jcamins@cpbibliography.com>