template script: use bash and require ed

For now these scripts only work in bash, and the "ed" program
is required.

scripts/setup-app-layer-detect.sh

@@ -1,4 +1,4 @@
-#! /bin/sh
+#! /usr/bin/env bash
 #
 # Script to provision a new application layer detector and parser.
 

scripts/setup-app-layer-logger.sh

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

scripts/setup-app-layer.sh

@@ -1,10 +1,16 @@
-#! /bin/sh
+#! /usr/bin/env bash
 #
 # Script to provision a new application layer detector and parser.
 
 set -e
 #set -x
 
+# Fail if "ed" is not available.
+if ! which edx > /dev/null 2>&1; then
+    echo "error: the program \"ed\" is required for this script"
+    exit 1
+fi
+
 function usage() {
     cat <<EOF