Bug 27476: Improve link text for logging in on OPAC

Bug 27476: Improve link text for logging in on OPAC

(Note: Must have Shibboleth and CAS added to OPAC)
1. (Before downloading patch) Go to OPAC
2. Search for an item in the search bar (i.e. type 'a')
3. On one of the items, click on 'Place hold'
4. The links should say 'If you have a Shibboleth account, please click
here to log in', 'Please click here to log in' and 'If you have a CAS
account, please click here to log in'
5. Add patch
6. Repeat steps 1-3
7. The links should now say 'Log in using a Shibboleth account', 'Log in'
and 'Log in using a CAS account'

NOTE: Also noticed on the initial log in box there was the same issue -
here is the testing for that:
1. Go to OPAC home page
2. In the top right click 'Log in to your account'
3. The link should say 'If you have a Shibboleth account, please click
here to log in.'
4. Apply patch
5. Repeat steps 1&2
6. The link should now say 'Log in using a Shibboleth account'

Sponsored-by: Catalyst IT
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>