Bug 34706: Fix capitalization - Cas to CAS

Bug 34706: Fix capitalization - Cas to CAS

CAS is an abbreviation and should use capital letters.

Test plan:
1. Enable the casAuthentication system preference.
2. Logout and view the login form.
3. Note that it says "Cas login".
4. Apply the patch.
5. Refresh the login page.
6. Note that it now says "CAS login".
7. Sign off.

Signed-off-by: David Nind <david@davidnind.com>
Signed-off-by: Sam Lau <samalau@gmail.com>
Signed-off-by: Emily Lamancusa <emily.lamancusa@montgomerycountymd.gov>
Signed-off-by: Katrin Fischer <katrin.fischer@bsz-bw.de>
(cherry picked from commit 18e8f95bc5c533e27558bb004c7c131f5aef9fb3)
Signed-off-by: Lucas Gass <lucas@bywatersolutions.com>
(cherry picked from commit 4f2748b72c4d19be3ccf4baddc9764de523572bb)
Signed-off-by: Fridolin Somers <fridolin.somers@biblibre.com>