Bug 9032: (follow-up) add support for bootstrap theme

Bug 9032: (follow-up) add support for bootstrap theme

Adds new template opac-shareshelf.tt.
Modifies template opac-shelves.tt: Share button, Remove Share button,
label "Your lists" instead of "Your private lists", list category
Shared.

Test plan:
Verify if the Share a list-features work in bootstrap by:
[1] Switch to bootstrap. Go to Lists.
[2] Share one of your private lists.
[3] Login as another user and accept the invitation.
[4] Remove the share again.
[5] Check if Share and Remove share do not popup for public lists.

Signed-off-by: Dobrica Pavlinusic <dpavlin@rot13.org>
Signed-off-by: Jonathan Druart <jonathan.druart@biblibre.com>
Signed-off-by: Galen Charlton <gmc@esilibrary.com>