Update the MAINTAINERS file too, while I'm at it.

MAINTAINERS

-Overall Maintainers:
-Chenthill P <pchenthill@novell.com>
-Matthew Barnes <mbarnes@redhat.com>
-
-Mail:
-Matthew Barnes <mbarnes@redhat.com> 
-
-Addressbook:
-Srinivasa Ragavan <sragavan@novell.com>
-
-Calendar
-Chenthill P <pchenthill@novell.com>
-
-Shell:
-Srinivasa Ragavan <sragavan@novell.com>
 Matthew Barnes <mbarnes@redhat.com>
+Milan Crha <mcrha@redhat.com>
 
 User Documentation:
 Andre Klapper <ak-47@gmx.net>