Align dashboard nav items (#2380)

The `Overview` and `Resources` nav items were slightly out of alignment
with the other nav items.

Add paddingRight to the other nav items, to compensate for their
shrunken icons.

Signed-off-by: Andrew Seigner <siggy@buoyant.io>

web/app/js/components/Navigation.jsx

@@ -121,6 +121,7 @@ const styles = theme => {
     shrinkIcon: {
       fontSize: "18px",
       paddingLeft: "3px",
+      paddingRight: "3px",
     }
   };
 };