Undo changes made in the 'tools' subtree

This is vendor'd in from weaveworks/build-tools so must not be changed
here.

tools/socks/Dockerfile

@@ -1,5 +1,5 @@
 FROM gliderlabs/alpine
-LABEL maintainer="Weaveworks Inc <help@weave.works>"
+MAINTAINER Weaveworks Inc <help@weave.works>
 WORKDIR /
 COPY proxy /
 EXPOSE 8000

tools/socks/main.go

@@ -8,10 +8,10 @@ import (
 	"strings"
 	"text/template"
 
-	"context"
 	socks5 "github.com/armon/go-socks5"
 	"github.com/weaveworks/common/mflag"
 	"github.com/weaveworks/common/mflagext"
+	"golang.org/x/net/context"
 )
 
 type pacFileParameters struct {