Bug 37209: improve Record overlay rules validation and styling

Bug 37209: improve Record overlay rules validation and styling

This patch adds jquery form validation to the input named tag. It also changes the behavior for save and edit actions which now both can be triggered by pressing enter. Batch deletion will be only possible if no edit is taking place.

Test plan:
1)
 a) open http://localhost:8081/cgi-bin/koha/admin/marc-overlay-rules.pl
 b) just click + Add rule
 c) the input 'tag' gets highlighted and the form won't submit

2)
 a) edit an existing rule
 b) empty input value for tag
 c) notice the checkboxes for batch deletion on other rules if existing
 d) click Save and check the input 'tag' gets highlighted and the form won't submit

apply patch
1) redo steps and check that form does not get submitted and the input is marked as required via a label that says This field is required.

2) redo steps and check that form does not get submitted and the input is marked as required via a label that says This field is required. Also checkboxes for batchremove actions are gone.

Signed-off-by: Olivier Vezina <olivier.vezina@inLibro.com>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>
Signed-off-by: Katrin Fischer <katrin.fischer@bsz-bw.de>