Refactor to older versions of bash that don't have associative array

support, so that this works on OS/X.

 #!/usr/bin/env bash
+# OS/X does not include GPLv3 versions of bash, which precludes
+# use of associative array support.
 
 set -e
 
-declare -A defaults=(
-	[INKLUSTER_IMAGE]=brainfood/inkluster-dev
-	[INKLUSTER_VOLUME_NAME]=""
-)
+DEFAULT_INKLUSTER_IMAGE=brainfood/inkluster-dev
+DEFAULT_INKLUSTER_VOLUME_NAME=""
+if [[ -e values/apiserver-env.yaml ]]; then
+	buildName="$(sed -n -e 's/^buildName: "\(.*\)"$/\1/p' "values/apiserver-env.yaml")"
+	[[ $buildName ]] && DEFAULT_INKLUSTER_VOLUME_NAME="$buildName"
+fi
 
+declare -a config_keys=(INKLUSTER_IMAGE INKLUSTER_VOLUME_NAME)
 declare -a config_files=()
 
 if [[ -e .inkluster.env ]]; then
 	config_files+=("$PWD/.inkluster.env")
 fi
 
-declare -A config=()
-
 # This copies ENV settings into the config, that haven't been set on the command line.
-for setting in "${!defaults[@]}"; do
-	[[ ${!setting} ]] && eval config[$setting]="${!setting}"
+for setting in "${config_keys[@]}"; do
+	[[ ${!setting} ]] && eval CONFIG_$setting='"${!'setting'}"'
 done
 
 declare -a REST=()
@@ -28,11 +31,11 @@ while [[ $# -gt 0 ]]; do
 			shift 2
 			;;
 		(-i)
-			config[INKLUSTER_IMAGE]="$2"
+			CONFIG_INKLUSTER_IMAGE="$2"
 			shift 2
 			;;
 		(-v)
-			config[INKLUSTER_VOLUME_NAME]="$2"
+			CONFIG_INKLUSTER_VOLUME_NAME="$2"
 			shift 2
 			;;
 		(*)
@@ -57,10 +60,12 @@ for config_file in "${config_files[@]}"; do
 done
 
 # Any settings read from the config files, but not yet set, get applied.
-for setting in "${!defaults[@]}"; do
-	[[ -n ${!setting} && -z ${config[$setting]} ]] && eval config[$setting]="${!setting}"
-	[[ -z ${config[$setting]} ]] && eval config[$setting]="${defaults[$setting]}"
-	eval $setting=\"\${config[$setting]}\"
+for setting in "${config_keys[@]}"; do
+	if eval [[ '${CONFIG_'$setting'}' ]]; then
+		eval $setting='"${CONFIG_'$setting'}"'
+	else
+		[[ -z ${!setting} ]] && eval $setting='"${DEFAULT_'$setting'}"'
+	fi
 done
 
 has_volume=