bug #4558 Unable to Add Rows while Creating Table

- Remove inline JS from add column button.
- Remove unnecessary eventhandler to submit form on enter.
- Added event handler to add column field to add on enter.
- Fix tests

Signed-off-by: Nisarg Jhaveri <nisarg.jhaveri@research.iiit.ac.in>
Merge pull request #1378 from nisargjhaveri/bug_4558

bug #4558 Unable to Add Rows while Creating Table
ChangeLog entry

Signed-off-by: Marc Delisle <marc@infomarc.info>