Bug 15288: (followup) Remove obsolete *.tt files

 Bug 15288: (followup) Remove obsolete *.tt files

Follwoing files were not yet deleted:

koha-tmpl/opac-tmpl/bootstrap/en/modules/errors/400.tt
koha-tmpl/opac-tmpl/bootstrap/en/modules/errors/401.tt
koha-tmpl/opac-tmpl/bootstrap/en/modules/errors/402.tt
koha-tmpl/opac-tmpl/bootstrap/en/modules/errors/403.tt
koha-tmpl/opac-tmpl/bootstrap/en/modules/errors/500.tt

Note: the 404.tt file was renamed to errorpage.tt

To test: Verify that files are deleted.

Signed-off-by: Hector Castro <hector.hecaxmmx@gmail.com>
Files removed, new errorpage.tt added

Signed-off-by: Marcel de Rooy <m.de.rooy@rijksmuseum.nl>
Signed-off-by: Brendan A Gallagher <brendan@bywatersolutions.com>