CAS-1316: Refactor MessageSender to become its own class, in order to decouple HttpClient dependency on SLO messages.
CAS-1316: Added missing copyright block
CAS-1316: added javadoc for the class.
CAS-1455: Update to pac4j 1.5.1

First commit
Merge branch 'master' into CAS-1316

Conflicts:
	cas-server-core/src/main/java/org/jasig/cas/logout/LogoutManagerImpl.java
	cas-server-core/src/main/java/org/jasig/cas/util/SimpleHttpClient.java
CAS-1316: Merged with master. Refactored
CAS-1316: added additional timeout settings for the httpclient
CAS-1316: moved the task of sending messages to the httpclient
CAS-1316: fixed property name
CAS-1316: fixed prop access
CAS-1316: fixed spelling issue
CAS-1451: Align ticket cleaner & logout mgmr's SLO setting
CAS-1430: New switch-case transformer component

https://issues.jasig.org/browse/CAS-1430
CAS-1451: fixed test failures
Merge pull request #433 from leleuj/CAS-1455

CAS-1455: Update to pac4j 1.5.1
CAS-1430: Added test cases
Merge pull request #435 from Unicon/CAS-1430

CAS-1430: New switch-case transformer component
CAS-1461: Upgrade to v1.5.2
Merge pull request #440 from Unicon/CAS-1461

CAS-1461: Upgrade to PersonDirectory v1.5.2
CAS-1462: Upgrade Spring/SWF dependencies to 4.x and 2.3.3