ISPN-2985 Allow passing in a pre-built SSLContext to the HotRod server/client

This is a small PR to simplify the previous ISPN-907 commit and to ease server integration. Don't close the Jira until the corresponding infinispan-server PR is handled

https://issues.jboss.org/browse/ISPN-2985

Required for https://github.com/infinispan/infinispan-server/pull/92