Update foamgrid maintainers

dune.module

@@ -5,7 +5,7 @@
 #Name of the module
 Module: dune-foamgrid
 Version: 2.6-git
-Maintainer: sander@igpm.rwth-aachen.de
+Maintainer: timo.koch@iws.uni-stuttgart.de, oliver.sander@tu-dresden.de
 #depending on
 Depends: dune-common (>= 2.5) dune-geometry (>= 2.5) dune-grid (>= 2.5)
 Suggests: dune-corepy