added warning in h2o-n2 fluidsystem: Gas phase viscosity does not depend on composition so far

git-svn-id: svn://svn.iws.uni-stuttgart.de/DUMUX/dumux/trunk@6030 2fb0f335-1f38-0410-981e-8018bf24f1b0

dumux/material/fluidsystems/h2o_n2_system.hh

@@ -184,6 +184,7 @@ public:
                                         pressure);
         }
         else {
+#warning "TODO: Viscosity of gas phase does not depend on composition!"
             return N2::gasViscosity(temperature,
                                     pressure);
             /* Wilke method. See: