Move to vendor

Signed-off-by: Olivier Gambier <olivier@docker.com>

Dockerfile

@@ -1,11 +1,10 @@
-FROM golang:1.5.3
+FROM golang:1.6
 
 RUN apt-get update && \
     apt-get install -y apache2-utils && \
     rm -rf /var/lib/apt/lists/*
 
 ENV DISTRIBUTION_DIR /go/src/github.com/docker/distribution
-ENV GOPATH $DISTRIBUTION_DIR/Godeps/_workspace:$GOPATH
 ENV DOCKER_BUILDTAGS include_oss include_gcs
 
 WORKDIR $DISTRIBUTION_DIR