Allow overrides for ETCD ports

This will enable us to run one etcd for devstack and another
for kubernetes in the same box if necessary

Change-Id: Ib71ded24727b80afd4d98eb68bade0f8c0f72311
diff --git a/stackrc b/stackrc
index ffe4050..ed356ee 100644
--- a/stackrc
+++ b/stackrc
@@ -748,6 +748,8 @@
 else
     exit_distro_not_supported "invalid hardware type - $ETCD_ARCH"
 fi
+ETCD_PORT=${ETCD_PORT:-2379}
+ETCD_PEER_PORT=${ETCD_PEER_PORT:-2380}
 ETCD_DOWNLOAD_URL=${ETCD_DOWNLOAD_URL:-https://github.com/coreos/etcd/releases/download}
 ETCD_NAME=etcd-$ETCD_VERSION-linux-$ETCD_ARCH
 ETCD_DOWNLOAD_FILE=$ETCD_NAME.tar.gz