fixes #39 - use openssl to generate passwd for mysql

stack.sh

@@ -135,7 +135,7 @@ LIBVIRT_TYPE=${LIBVIRT_TYPE:-kvm}
 
 # Mysql connection info
 MYSQL_USER=${MYSQL_USER:-root}
-MYSQL_PASS=${MYSQL_PASS:-nova}
+MYSQL_PASS=${MYSQL_PASS:-`openssl rand -hex 12`}
 MYSQL_HOST=${MYSQL_HOST:-localhost}
 # don't specify /db in this string, so we can use it for multiple services
 BASE_SQL_CONN=${BASE_SQL_CONN:-mysql://$MYSQL_USER:$MYSQL_PASS@$MYSQL_HOST}