Bug 21645: Clean up library groups template

Bug 21645: Clean up library groups template

This patch modifies the library groups administration page to help
compliance with several coding guidelines:

 - Move JavaScript to the footer
 - Convert to Bootstrap grid
 - Other markup corrections

To test, apply the patch and go to Administration -> Library groups.

 - Confirm that the page how has a "Library groups" heading.
 - Confirm that action buttons in the table of library groups are styled
   correctly.
 - Test both adding and editing groups. The "Required" label on required
   fields should be styled correctly.
 - Test all JavaScript-driven interactions on the page:
   - Adding, editing, and deleting groups
   - Removing libraries from groups
   - Expanding and collapsing group hierarchies
 - Validate the page's HTML and confirm that there are no errors found
   in the main body of the page.

Signed-off-by: Mark Tompsett <mtompset@hotmail.com>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Signed-off-by: Nick Clemens <nick@bywatersolutions.com>