Remove the DFW default region.

DFW doesn't make sense for non-Rackspace providers, so away it goes.
All the tests run for me without it.
diff --git a/acceptance/03-get-server-details.go b/acceptance/03-get-server-details.go
index 88d7978..9d534ef 100644
--- a/acceptance/03-get-server-details.go
+++ b/acceptance/03-get-server-details.go
@@ -7,7 +7,7 @@
 )
 
 var id = flag.String("i", "", "Server ID to get info on.  Defaults to first server in your account if unspecified.")
-var rgn = flag.String("r", "DFW", "Datacenter region")
+var rgn = flag.String("r", "", "Datacenter region.  Leave blank for default region.")
 var quiet = flag.Bool("quiet", false, "Run quietly, for acceptance testing.  $? non-zero if issue.")
 
 func main() {
@@ -107,4 +107,4 @@
 	}
 	err = waitForServerState(servers, serverId, "ACTIVE")
 	return true, serverId, err
-}
\ No newline at end of file
+}