Remove the old bills interface.

Remove the old bills interface.

Remove the old bills interface and references to it.

see https://bugs.launchpad.net/evergreen/+bug/854951

Also remove the XUL_PATRON_BILL_ALTERNATE_VIEW constant and the
bills_main_view receipt template, as they were only referenced
in bills.js.

The bills_main_view template will still persist in existing
workstation configurations until such time as we have code to
remove unused templates.

I made no effort to remove strings which may have only been used
by the old bills interface.

Signed-off-by: Jeff Godin <jgodin@tadl.org>