Openfire Hazelcast (clustering) Plugin 3.1.0 Release

• [Issue #105] - Maximum cache size (in bytes) incorrectly reported
• [Issue #103] - Fix Cluster initialization race condition
• [Issue #102] - Remove unused code in ClusterListener
• [Issue #81] - ClusterExternalizableUtil should not ignore provided ClassLoader instances
• [Issue #79] - Use plugin classloader when executing task defined in a plugin