Let the JBoss clustered session manager handle session expiration (TORQUE-1201)

Expiring keys behind the clustered session manager's back in
Infinispan leads to early session timeouts and in certain conditions
errors upon restarting a clustered TorqueBox.

This change also removes the default expiration (of less than 2
minutes) for regular Infinispan cache keys, instead relying on Ruby
clients to specify a cache expiration when adding entries.