add helper script to enable wterl

Add a helper script to enable wterl in a riak devrel build. The script is
meant to be temporary, to be used during wterl development.

enable-wterl

@@ -0,0 +1,59 @@
+#!/bin/sh
+
+# This script adds wterl to a riak github repo. Run it in the riak repo
+# directory.
+#
+# First it adds wterl, then runs "make all devrel" and then enables the
+# wterl storage backend in the resulting dev nodes.
+#
+# This script is intended to be temporary. Once wterl is made into a proper
+# riak citizen, this script will no longer be needed.
+
+set -e
+
+wd=`pwd`
+if [ `basename $wd` != riak ]; then
+    echo "This doesn't appear to be a riak repo directory. Exiting."
+    exit 1
+fi
+
+if [ -d dev ]; then
+    echo
+    echo 'NOTE: THIS SCRIPT WILL DELETE YOUR EXISTING DEV DIRECTORY!'
+    while [ 1 ]; do
+        printf '\n%s' '  Do you wish to proceed? [no] '
+        read answer
+        answer=${answer:-n}
+        case $answer in
+            [Nn]*) exit 0 ;;
+            [Yy]*) break ;;
+            *) echo 'Please answer y or n.' ;;
+        esac
+    done
+fi
+
+rebar get-deps
+
+file=./deps/riak_kv/rebar.config
+if ! grep -q wterl $file ; then
+    echo
+    echo "Modifying $file, saving the original as ${file}.orig ..."
+    perl -i.orig -pe '/\bsext\b/ && print qq(        {wterl, ".*", {git, "git\@github.com:basho/wterl.git", "master"}},\n)' $file
+fi
+file=./deps/riak_kv/src/riak_kv.app.src
+if ! grep -q wterl $file ; then
+    echo
+    echo "Modifying $file, saving the original as ${file}.orig ..."
+    perl -i.orig -pe '/\briak_pipe\b/ && print "                  wterl,\n"' $file
+fi
+
+rebar get-deps
+
+rm -rf dev
+make all devrel
+
+echo
+echo 'Modifying all dev/dev*/etc/app.config files, saving originals with .orig suffix...'
+perl -i.orig -ne 'if (/\bstorage_backend,/) { s/(storage_backend, )[^\}]+/\1riak_kv_wterl_backend/; print } elsif (/\{eleveldb,/) { $eleveldb++; print } elsif ($eleveldb && /^\s+\]\},/) { $eleveldb = 0; print; print qq(\n {wterl, [\n          {data_root, "./data/wt"}\n         ]},\n\n) } else { print }' dev/dev*/etc/app.config
+
+exit 0