replace use of cirros 0.3.0 with 0.3.1

cirros 0.3.1 images have several significant improvements over 0.3.0, including:
 * newer kernel (3.2.0-25.40)
 * support for more filesystems (vfat, iso9660)
 * support for configdrive (config-drive-v2) as a datasource
 * acpi reboot/shutdown
 * curl with https support (previously there was no way to get https urls)

Change-Id: Idd7bef0cebb941f77d1cead9dc990fa0b03ff46b
diff --git a/stackrc b/stackrc
index 91f4e2b..2ee7d18 100644
--- a/stackrc
+++ b/stackrc
@@ -167,12 +167,12 @@
 #    glance as a disk image.  If it ends in .gz, it is uncompressed first.
 #    example:
 #      http://cloud-images.ubuntu.com/releases/oneiric/release/ubuntu-11.10-server-cloudimg-armel-disk1.img
-#      http://launchpad.net/cirros/trunk/0.3.0/+download/cirros-0.3.0-x86_64-rootfs.img.gz
+#      http://download.cirros-cloud.net/0.3.1/cirros-0.3.1-x86_64-rootfs.img.gz
 #  * OpenVZ image:
 #    OpenVZ uses its own format of image, and does not support UEC style images
 
 #IMAGE_URLS="http://smoser.brickies.net/ubuntu/ttylinux-uec/ttylinux-uec-amd64-11.2_2.6.35-15_1.tar.gz" # old ttylinux-uec image
-#IMAGE_URLS="http://launchpad.net/cirros/trunk/0.3.0/+download/cirros-0.3.0-x86_64-disk.img" # cirros full disk image
+#IMAGE_URLS="http://download.cirros-cloud.net/0.3.1/cirros-0.3.1-x86_64-disk.img" # cirros full disk image
 
 # Set default image based on ``VIRT_DRIVER`` and ``LIBVIRT_TYPE``, either of
 # which may be set in ``localrc``.  Also allow ``DEFAULT_IMAGE_NAME`` and
@@ -184,16 +184,16 @@
     libvirt)
         case "$LIBVIRT_TYPE" in
             lxc) # the cirros root disk in the uec tarball is empty, so it will not work for lxc
-                DEFAULT_IMAGE_NAME=${DEFAULT_IMAGE_NAME:-cirros-0.3.0-x86_64-rootfs}
-                IMAGE_URLS=${IMAGE_URLS:-"http://launchpad.net/cirros/trunk/0.3.0/+download/cirros-0.3.0-x86_64-rootfs.img.gz"};;
+                DEFAULT_IMAGE_NAME=${DEFAULT_IMAGE_NAME:-cirros-0.3.1-x86_64-rootfs}
+                IMAGE_URLS=${IMAGE_URLS:-"http://download.cirros-cloud.net/0.3.1/cirros-0.3.1-x86_64-rootfs.img.gz"};;
             *) # otherwise, use the uec style image (with kernel, ramdisk, disk)
-                DEFAULT_IMAGE_NAME=${DEFAULT_IMAGE_NAME:-cirros-0.3.0-x86_64-uec}
-                IMAGE_URLS=${IMAGE_URLS:-"http://launchpad.net/cirros/trunk/0.3.0/+download/cirros-0.3.0-x86_64-uec.tar.gz"};;
+                DEFAULT_IMAGE_NAME=${DEFAULT_IMAGE_NAME:-cirros-0.3.1-x86_64-uec}
+                IMAGE_URLS=${IMAGE_URLS:-"http://download.cirros-cloud.net/0.3.1/cirros-0.3.1-x86_64-uec.tar.gz"};;
         esac
         ;;
     *) # otherwise, use the uec style image (with kernel, ramdisk, disk)
-        DEFAULT_IMAGE_NAME=${DEFAULT_IMAGE_NAME:-cirros-0.3.0-x86_64-uec}
-        IMAGE_URLS=${IMAGE_URLS:-"http://launchpad.net/cirros/trunk/0.3.0/+download/cirros-0.3.0-x86_64-uec.tar.gz"};;
+        DEFAULT_IMAGE_NAME=${DEFAULT_IMAGE_NAME:-cirros-0.3.1-x86_64-uec}
+        IMAGE_URLS=${IMAGE_URLS:-"http://download.cirros-cloud.net/0.3.1/cirros-0.3.1-x86_64-uec.tar.gz"};;
 esac
 
 # 5Gb default volume backing file size