Update jwqldb page with django model names

[bhilbert4]

Remove old sqlalchemy db table names and replace with Django model names.
This also removes another call to database_interface and sqlalchemy.
Also tweak drop-down menu to show the name of the displayed table rather than reverting to show the first table name in the list.

[bhilbert4]

@mfixstsci I think this is ready for review. I started by trying to figure out the issue with the jwqldb page that Katie Bechtold was having. But with the service out of commission on the test server, it was hard to investigate. Then I realized that the pull down menu of table names was still referring to sqlalchemy names, and the code included a call to database_interface. So I pivoted to updating the page to use Django models. Everything works for me locally. Hopefully this will resolve the issue.