Bug 16401: System preference staffClientBaseURL hardcoded to 'http://'

Bug 16401: System preference staffClientBaseURL hardcoded to ''

Test plan:
1) Insert some value to staffBaseURL preference, without starting http://
2) Apply the patch
3) Update database
4) Go to system preferences adminsitration, find the staffBaseURL
preference, the inserted value should be prepended with 'http://' and
the comment should be "This should be a complete URL, starting with
http:// or https://. Do not include a trailing slash in the URL. (This
must be filled in correctly for CAS, svc, and load_testing to work.)"
5) prove t/db_dependent/Auth_with_cas.t
6) prove t/db_dependent/selenium/basic_workflow.t
7) prove t/db_dependent/check_sysprefs.t

Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Nick Clemens <nick@bywatersolutions.com>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>