Pin all tools used in the Dockerfiles

Also update gometalinter to use the official version. The update
found some new gosimple errors, which are fixed.

Also update the filewatcher script for the latest version of filewatcher.

Signed-off-by: Daniel Nephin <dnephin@docker.com>

scripts/test/watch

@@ -1,12 +1,2 @@
 #!/bin/sh
-
-set -e
-
-filewatcher \
-    -L 6 \
-    -x '**/*.swp' \
-    -x .git \
-    -x build \
-    -x .idea \
-    -- \
-    sh -c 'go test -timeout 10s -v ./${dir} || ( echo; echo; exit 1 )'
+exec filewatcher -L 6 -x build -x script go test -timeout 10s -v './${dir}'