Exposing EHCache over JMX.

Original issue was closed with remark
EHCache "being already exposed via REST".

This is true for NFC cache only. This
solution exposes all cache stats (with some
slight change might do even more), and allows
inspection of caches used by Shiro too
(as it uses 3 caches in OSS and more in Pro).

Signed-off-by: Tamas Cservenak <tamas@cservenak.net>