Make JpaStore class loader for entity class configurable

JpaStore entity class is loaded using Infinispan's class loader. This is not ideal in environments such as OSGi where Infinispan and entities may locate in different class loaders.

My workaround was to patch JpaStoreConfigurationParser71.parseJpaCacheStore to utilize the entity class loader I has earlier passed to configuration builder holder. By default it seems to point to thread class loader so it should work in modern OSGi environments out-of-the-box.