Add support for mkinitcpio

https://bugzilla.gnome.org/show_bug.cgi?id=710682

src/boot/ostree-prepare-root.service

@@ -0,0 +1,32 @@
+# Copyright (C) 2013 Colin Walters <walters@verbum.org>
+#
+# This library is free software; you can redistribute it and/or
+# modify it under the terms of the GNU Lesser General Public
+# License as published by the Free Software Foundation; either
+# version 2 of the License, or (at your option) any later version.
+#
+# This library is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+# Lesser General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public
+# License along with this library; if not, write to the
+# Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+# Boston, MA 02111-1307, USA.
+
+[Unit]
+Description=OSTree Prepare OS/
+DefaultDependencies=no
+ConditionKernelCommandLine=ostree
+ConditionPathExists=/etc/initrd-release
+OnFailure=emergency.service
+After=initrd-switch-root.target
+Before=initrd-switch-root.service
+
+[Service]
+Type=oneshot
+ExecStart=/usr/sbin/ostree-prepare-root /sysroot
+StandardInput=null
+StandardOutput=syslog
+StandardError=syslog+console