add CAS support: step 1, get /auth/login
add CAS support: step 2, add 'get /auth/cas'
add CAS support: step 3, add module auth_cas.rb
add CAS support: step 4, add options in KibanaConfig.rb
add CAS support: step 5, rubycas-client dependency in gemspec
add CAS support: step 6, Add a cas button
Go to /auth/admin when you clic on "User Administration"
Go to /auth/admin when you clic on "User Administration" and not /auth/admon \!
final touch to CAS SSO
No need to default url value
No need to define cas_url
Delete unnecessary method from auth_cas.rb