Copy download-or-bust helper from gce to aws

During a push, we were wget-ing to <filename>.1, .2, etc, which wasn't working

cluster/aws/templates/common.sh

@@ -0,0 +1,29 @@
+#!/bin/bash
+
+# Copyright 2015 Google Inc. All rights reserved.
+#
+# 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.
+
+# Retry a download until we get it.
+#
+# $1 is the URL to download
+download-or-bust() {
+  local -r url="$1"
+  local -r file="${url##*/}"
+  rm -f "$file"
+  until [[ -e "${1##*/}" ]]; do
+    echo "Downloading file ($1)"
+    curl --ipv4 -Lo "$file" --connect-timeout 20 --retry 6 --retry-delay 10 "$1"
+    md5sum "$file"
+  done
+}

cluster/aws/templates/download-release.sh

@@ -21,10 +21,10 @@
 # master and run.
 
 echo "Downloading binary release tar ($SERVER_BINARY_TAR_URL)"
-wget "$SERVER_BINARY_TAR_URL"
+download-or-bust "$SERVER_BINARY_TAR_URL"
 
 echo "Downloading binary release tar ($SALT_TAR_URL)"
-wget "$SALT_TAR_URL"
+download-or-bust "$SALT_TAR_URL"
 
 echo "Unpacking Salt tree"
 rm -rf kubernetes