bugfix: Explicitly use bash

Change-Id: Idbf856991e6a503246c4621aead93024264122ea
diff --git a/setup-ramcloud.sh b/setup-ramcloud.sh
index 08e91d2..9a91cc2 100755
--- a/setup-ramcloud.sh
+++ b/setup-ramcloud.sh
@@ -1,4 +1,4 @@
-#!/bin/sh
+#!/bin/bash
 
 # fail on command error
 set -e