Update for docker/machine PR #1729

[tomwilkie]

docker/machine#1729

Broke:

package github.com/weaveworks/weave/...
    imports github.com/weaveworks/weave/common
    imports github.com/weaveworks/weave/common/docker
    imports github.com/weaveworks/weave/common/mflagext
    imports github.com/docker/docker/pkg/mflag
    imports github.com/docker/docker/pkg/homedir
    imports github.com/weaveworks/weave/ipam
    imports github.com/andybalholm/go-bit
    imports github.com/google/gopacket
    imports github.com/google/gopacket/layers
    imports github.com/google/gopacket/pcap
    imports github.com/gorilla/mux
    imports github.com/gorilla/context
    imports golang.org/x/crypto/nacl/box
    imports github.com/weaveworks/weave/nameserver
    imports github.com/weaveworks/weave/net
    imports github.com/vishvananda/netlink
    imports github.com/weaveworks/weave/prog/weaver
    imports github.com/weaveworks/weave/test/tls
    imports github.com/docker/machine/utils
    imports github.com/docker/machine/utils
    imports github.com/docker/machine/utils: cannot find package "github.com/docker/machine/utils" in any of:
    /usr/local/go/src/github.com/docker/machine/utils (from $GOROOT)
    /home/ubuntu/src/github.com/docker/machine/utils (from $GOPATH)
    /home/ubuntu/.go_workspace/src/github.com/docker/machine/utils

[tomwilkie]

This should probably target 1.1 thinking about it. 1 sec.