Remove bash-isms in cloud build scripts

Signed-off-by: Nathan LeClaire <nathan.leclaire@gmail.com>

alpine/cloud/Dockerfile.ami

@@ -3,7 +3,6 @@ FROM alpine
 RUN apk add --update \
     python \
     py-pip \
-    bash \
     curl \
     e2fsprogs \
     jq \

alpine/cloud/Dockerfile.azure

@@ -1,7 +1,6 @@
 FROM golang:alpine
 
 RUN apk add --update \
-    bash \
     curl \
     e2fsprogs \
     syslinux \

alpine/cloud/aws/approve-account.sh

@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/bin/sh
 
 # Usage: ./aws/approve-account.sh [ACCOUNT_ID] [AMI_FILE]
 #

alpine/cloud/aws/bake-ami.sh

@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/bin/sh
 
 # Script to automate creation and snapshotting of a Moby AMI.  Currently, it's
 # intended to be invoked from an instance running in the same region as the
@@ -7,7 +7,7 @@
 
 set -e
 
-declare -xr PROVIDER="aws"
+PROVIDER="aws"
 
 source "./build-common.sh"
 source "${MOBY_SRC_ROOT}/cloud/aws/common.sh"
@@ -84,7 +84,7 @@ clean_tagged_resources()
 	fi
 
 	VOLUME_ID=$(aws ec2 describe-volumes --filters "Name=tag-key,Values=$1" | jq -r .Volumes[0].VolumeId)
-	if [ ${VOLUME_ID} == "null" ]
+	if [ ${VOLUME_ID} = "null" ]
 	then
 		arrowecho "No volume found, skipping"
 	else
@@ -96,7 +96,7 @@ clean_tagged_resources()
 	fi
 
 	IMAGE_ID=$(aws ec2 describe-images --filters "Name=tag-key,Values=$1" | jq -r .Images[0].ImageId)
-	if [ ${IMAGE_ID} == "null" ]
+	if [ ${IMAGE_ID} = "null" ]
 	then
 		arrowecho "No image found, skipping"
 	else
@@ -110,7 +110,7 @@ clean_tagged_resources()
 	fi
 
 	SNAPSHOT_ID=$(aws ec2 describe-snapshots --filters "Name=tag-key,Values=$1" | jq -r .Snapshots[0].SnapshotId)
-	if [ ${SNAPSHOT_ID} == "null" ]
+	if [ ${SNAPSHOT_ID} = "null" ]
 	then
 		arrowecho "No snapshot found, skipping"
 	else

alpine/cloud/aws/common.sh

@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/bin/sh
 
 set -e
 

alpine/cloud/aws/copy-amis.sh

@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/bin/sh
 
 # Usage: ./cloud/aws/copy-amis.sh 
 # Assumptions: 

alpine/cloud/aws/run-instance.sh

@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/bin/sh
 
 # Quick script to boot an instance from generated AMI.  Intended to be invoked
 # from "alpine" directory.
@@ -18,7 +18,7 @@ manager_sg_id()
 attach_security_group()
 {
 	MANAGER_SG_ID=$(manager_sg_id)
-	if [ ${MANAGER_SG_ID} == "null" ]
+	if [ ${MANAGER_SG_ID} = "null" ]
 	then
 		CUR_INSTANCE_MAC=$(wget -qO- ${METADATA}/network/interfaces/macs)
 		CUR_INSTANCE_VPC_CIDR=$(wget -qO- ${METADATA}/network/interfaces/macs/${CUR_INSTANCE_MAC}vpc-ipv4-cidr-block)
@@ -56,7 +56,7 @@ poll_instance_log()
 	echo "Waiting for instance boot log to become available"
 
 	INSTANCE_BOOT_LOG="null"
-	while [ ${INSTANCE_BOOT_LOG} == "null" ]
+	while [ ${INSTANCE_BOOT_LOG} = "null" ]
 	do
 		INSTANCE_BOOT_LOG=$(aws ec2 get-console-output --instance-id "$1" | jq -r .Output)
 		sleep 5

alpine/cloud/azure/bake-azure.sh

@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/bin/sh
 
 # Script to automate the creation of a VHD for Moby in Azure, and upload it to
 # an Azure storage account (needed in order to launch it on Azure, or upload it
@@ -22,7 +22,7 @@
 
 set -e
 
-declare -xr PROVIDER="azure"
+PROVIDER="azure"
 
 source "build-common.sh"
 

alpine/cloud/build-common.sh

@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/bin/sh
 
 set -e
 
@@ -26,7 +26,7 @@ format_on_device()
 	# TODO (nathanleclaire): Any more readable or more elegant solution to
 	# account for this minor (specify 1st partition as bootable) difference
 	# between cloud builds?
-	if [ "${PROVIDER}" == "aws" ]
+	if [ "${PROVIDER}" = "aws" ]
 	then
 		# This heredoc might be confusing at first glance, so here is a detailed
 		# summary of what each line does:
@@ -49,7 +49,7 @@ a
 1
 w
 EOF
-	elif [ ${PROVIDER} == "azure" ]
+	elif [ ${PROVIDER} = "azure" ]
 	then
 		fdisk "$1" << EOF
 n