CAS-1389: Logout fails as an error happens when tickets are marked as expired

First commit
CAS-1389: Logout fails as an error happens when tickets are marked as expired

change debug message and add a test to confirm the correct behaviour
CAS-1389: Logout fails as an error happens when tickets are marked as expired

Updates after Misagh's code review
CAS-1393: Memcached serialization fails when creating a proxy ticket

First commit
CAS-1393: Memcached serialization fails when creating a proxy ticket

Update according to Marvin's code review
Merge pull request #365 from leleuj/CAS-1389

CAS-1389: Logout fails as an error happens when tickets are marked as expired
Merge pull request #367 from leleuj/CAS-1393

CAS-1393: Memcached serialization fails when creating a proxy ticket
Merge branch 'master' into JAVADOC-1
JAVADOC: Merged with master and adding missing javadocs