Bug 3134: add ability to selelct multiple reports to delete at once

Bug 3134: add ability to selelct multiple reports to delete at once

This patch adds the option to select multiple saved reports for
deletion.

To test you must have two or more saved reports to delete. Deletion
should work properly when:

- Selecting one report for deletion by checking the box.
- Selecting more than one report for deletion by checking boxes.
- Clicking the old "Delete" link

Clicking the delete button should prompt you to confirm. Clicking cancel
should cancel.

Clicking the delete button when no boxes are checked should trigger an
alert asking you to select reports for deletion.

Signed-off-by: Liz Rea <wizzyrea@gmail.com>
Functional tests pass, template tests pass.

Signed-off-by: Katrin Fischer <Katrin.Fischer.83@web.de>
Signed-off-by: Jonathan Druart <jonathan.druart@biblibre.com>
Signed-off-by: Galen Charlton <gmc@esilibrary.com>