Add systemd/fedora support to growroot

Add systemd/fedora support to growroot element.  This involves
installing the correct packages, shipping the systemd service file and
ensuring it is enabled.

Note the required growfs/resize packages for Ubuntu/Debian are
installed in other places.  This is probably a bug in that path, but I
have not addressed that here.

I have tested this with a F23 build with all openstack-infra elements,
uploaded to RAX, and it boots and resizes the main file-system.

Change-Id: I5630dc638f85b1e80795826ef36a306632075460

elements/growroot/init-scripts/systemd/growroot.service

@@ -0,0 +1,12 @@
+[Unit]
+Description=Grow root partition
+After=local-fs.target
+
+[Service]
+Type=oneshot
+User=root
+ExecStart=/usr/local/sbin/growroot
+RemainAfterExit=true
+
+[Install]
+WantedBy=multi-user.target

elements/growroot/package-installs.yaml

@@ -0,0 +1,2 @@
+growpart:
+e2fsprogs:

elements/growroot/pkg-map

@@ -0,0 +1,12 @@
+{
+    "family":{
+        "redhat": {
+            "growpart": "cloud-utils-growpart",
+            "e2fsprogs": "e2fsprogs"
+        },
+        "debian":{
+            "growpart": "cloud-utils",
+            "e2fsprogs": "e2fsprogs"
+        }
+    }
+}

elements/growroot/post-install.d/80-growroot

@@ -0,0 +1,21 @@
+#!/bin/bash
+
+if [ "${DIB_DEBUG_TRACE:-0}" -gt 0 ]; then
+    set -x
+fi
+set -eu
+set -o pipefail
+
+case "$DIB_INIT_SYSTEM" in
+    upstart)
+        # nothing to do
+        exit 0
+        ;;
+    systemd)
+        systemctl enable growroot.service
+        ;;
+    *)
+        echo "Unsupported init system"
+        exit 1
+        ;;
+esac