dockerfile: update deps and move to Go 1.6

Dockerfile

@@ -1,11 +1,26 @@
-FROM golang:1.5
+# Copyright 2015 clair authors
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+FROM golang:1.6
+
 MAINTAINER Quentin Machu <quentin.machu@coreos.com>
 
 RUN apt-get update && \
     apt-get install -y bzr rpm xz-utils && \
     apt-get autoremove -y && \
     apt-get clean && \
-    rm -rf /var/lib/apt/lists/* /tmp/* /var/tmp/*
+    rm -rf /var/lib/apt/lists/* /tmp/* /var/tmp/* # 18MAR2016
 
 VOLUME /config
 
@@ -14,7 +29,6 @@ EXPOSE 6060 6061
 ADD .   /go/src/github.com/coreos/clair/
 WORKDIR /go/src/github.com/coreos/clair/
 
-ENV GO15VENDOREXPERIMENT 1
 RUN go install -v github.com/coreos/clair/cmd/clair
 
 ENTRYPOINT ["clair"]