MAINTAINERS: update Ceph and RBD maintainers

- add Ilya, drop Yehuda as an RBD maintainer
- add Zheng as a Ceph maintainer
- update Yehuda and Sage's emails

Signed-off-by: Sage Weil <sage@redhat.com>

MAINTAINERS

@@ -2405,7 +2405,8 @@ F:	arch/powerpc/oprofile/*cell*
 F:	arch/powerpc/platforms/cell/
 
 CEPH DISTRIBUTED FILE SYSTEM CLIENT
-M:	Sage Weil <sage@inktank.com>
+M:	Yan, Zheng <zyan@redhat.com>
+M:	Sage Weil <sage@redhat.com>
 L:	ceph-devel@vger.kernel.org
 W:	http://ceph.com/
 T:	git git://git.kernel.org/pub/scm/linux/kernel/git/sage/ceph-client.git
@@ -7884,8 +7885,8 @@ S:	Odd Fixes
 F:	drivers/media/parport/*-qcam*
 
 RADOS BLOCK DEVICE (RBD)
-M:	Yehuda Sadeh <yehuda@inktank.com>
-M:	Sage Weil <sage@inktank.com>
+M:	Ilya Dryomov <idryomov@gmail.com>
+M:	Sage Weil <sage@redhat.com>
 M:	Alex Elder <elder@kernel.org>
 M:	ceph-devel@vger.kernel.org
 W:	http://ceph.com/