Make it possible to run rake gems:install for cas

The hard requires were causing rake to fail before it could even install
the rubycas-client gem. This kind of sucked.

app/controllers/application_controller.rb

@@ -33,11 +33,15 @@ class ApplicationController < ActionController::Base
     # This will allow the user to view the index page without authentication
     # but will process CAS authentication data if the user already
     # has an SSO session open.
+    if (CASClient rescue nil)
+      # Only require sub-library if gem is installed and loaded
+      require 'casclient/frameworks/rails/filter'
       before_filter CASClient::Frameworks::Rails::GatewayFilter, :only => :login
 
       # This requires the user to be authenticated for viewing all other pages.
       before_filter CASClient::Frameworks::Rails::Filter, :except => [:login , :calendar]
     end
+  end
   before_filter :set_session_expiration
   before_filter :set_time_zone
   before_filter :set_zindex_counter

config/environment.rb

@@ -65,9 +65,7 @@ Rails::Initializer.run do |config|
   # See Rails::Configuration for more options
   if ( SITE_CONFIG['authentication_schemes'].include? 'cas')
     #requires rubycas-client gem to be installed
-    config.gem "rubycas-client"
-    require 'casclient'
-    require 'casclient/frameworks/rails/filter'
+    config.gem "rubycas-client", :lib => 'casclient'
   end
 end
 
@@ -106,11 +104,14 @@ end
 
 if ( SITE_CONFIG['authentication_schemes'].include? 'cas')
   #requires rubycas-client gem to be installed
+  if (CASClient rescue nil)
+    require 'casclient/frameworks/rails/filter'
     CASClient::Frameworks::Rails::Filter.configure(
         :cas_base_url => SITE_CONFIG['cas_server'] ,
         :cas_server_logout => SITE_CONFIG['cas_server_logout']
       )
   end
+end
 
 tracks_version='1.8devel'
 # comment out next two lines if you do not want (or can not) the date of the