Bug 26687: Add a Font Awesome icon for superlibrarian patrons

Bug 26687: Add a Font Awesome icon for superlibrarian patrons

Bug 26534 adds a shield Font Awesome icon to help identify staff
patrons. I propose to add an icon when patron is a superlibrarian.

Patch adds 'is-superlibrarian' class that may be used for more CSS
tuning.

Test plan:
1) Compare display between a patron A beeing superlibarian and a patron
   B having only staff interface access
2) Patron B has only shield icon
3) Patron A has shield icon and bolt icon
4) Check a patron without permissions has no shield icon

Signed-off-by: Séverine QUEUNE <severine.queune@bulac.fr>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>