Update email address (#199)

package.xml

@@ -4,7 +4,7 @@
   <version>2.4.1</version>
   <description>Bindings between Numpy and Eigen using Boost.Python</description>
   <maintainer email="justin.carpentier@inria.fr">Justin Carpentier</maintainer>
-  <maintainer email="wolfgang@robots.ox.ac.uk">Wolfgang Merkt</maintainer>
+  <maintainer email="opensource@wolfgangmerkt.com">Wolfgang Merkt</maintainer>
   <author>Justin Carpentier</author>
   <author>Nicolas Mansard</author>
   <license>BSD</license>