Remove trailing whitespace (#1955)

Prevent future; "remove trailing whitespace" PR, but adding a simple
presubmit that checks for this.

This presubmit flagged quite some offenders, remove all trailing
whitespace from. Apart from that there aren't any other changes.

Signed-off-by: Miek Gieben <miek@miek.nl>

plugin/etcd/setup.go

@@ -124,7 +124,7 @@ func etcdParse(c *caddy.Controller) (*Etcd, bool, error) {
 		}
 		etc.Client = client
 		etc.endpoints = endpoints
-		
+
 		return &etc, stubzones, nil
 	}
 	return &Etcd{}, false, nil