Bug 13445: Remove URL option from scheduled reports, add Text option

Bug 13445: Remove URL option from scheduled reports, add Text option

Remove the non-functional 'URL' format
Offer the (functional) CSV & HTML formats

testing plan:
- visit the task scheduler tool at cgi-bin/koha/tools/scheduler.pl
- 'Output format' select list should offer Text (TSV), CSV, & HTML
- scheduled reports for each of the above types should run & send emails correctly

Signed-off-by: Mark Tompsett <mtompset@hotmail.com>
Signed-off-by: Maksim Sen <maksim.sen@inlibro.com>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>