Update GWL and DWK hostnames, remove dcgrouter

dns/hostfiles/routers

 # 10.205.253.0/24
 # amsw routers (loopback addressess)
 #
+# Not all routers use loopback addresses from this range! Some routers
+# (router-core.gwl.amsw.nl and router.wfc.amsw.nl at least) use public IPv4
+# addresses, others don't use a loopback address at all.
+#
 10.205.253.1 stanleyh
 10.205.253.2 duja
 10.205.253.3 trashbat
@@ -10,9 +14,8 @@
 10.205.253.7 nieuwlandrouter
 10.205.253.8 tristor
 10.205.253.9 soerel
-10.205.253.11 gwl
-10.205.253.12 dwk
+10.205.253.11 router-roof.gwl.amsw.nl
+10.205.253.12 router.dwk.amsw.nl
 10.205.253.13 hemelvaart
-10.205.253.14 bprouter # rtr01.lag.amsw.nl
-10.205.253.15 sofrouter # rtr01.sof.amsw.nl
-10.205.253.16 dcgrouter
+10.205.253.14 bprouter # router.lag.amsw.nl
+10.205.253.15 sofrouter # router.sof.amsw.nl