support non "uec style" IMAGE_URLS

This adds support for image urls that end in .img.gz or .img.
The assumption is that they're a full disk image or a compressed
disk image.

Some examples:
 https://cloud-images.ubuntu.com/server/releases/11.10/release/ubuntu-11.10-server-cloudimg-i386-disk1.img
 http://launchpad.net/cirros/trunk/0.3.0/+download/cirros-0.3.0-x86_64-rootfs.img.gz
 http://launchpad.net/cirros/trunk/0.3.0/+download/cirros-0.3.0-x86_64-disk.img

Change-Id: I79b67b461fb02f2403dad3e15f630fa9817eb0db
diff --git a/stackrc b/stackrc
index 524cc99..c420fc8 100644
--- a/stackrc
+++ b/stackrc
@@ -44,6 +44,18 @@
 CITEST_BRANCH=master
 
 # Specify a comma-separated list of uec images to download and install into glance.
+# supported urls here are:
+#  * "uec-style" images:
+#     If the file ends in .tar.gz, uncompress the tarball and and select the first
+#     .img file inside it as the image.  If present, use "*-vmlinuz*" as the kernel
+#     and "*-initrd*" as the ramdisk
+#     example: http://cloud-images.ubuntu.com/releases/oneiric/release/ubuntu-11.10-server-cloudimg-amd64.tar.gz
+#  * disk image (*.img,*.img.gz)
+#    if file ends in .img, then it will be uploaded and registered as a to
+#    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
 IMAGE_URLS=http://smoser.brickies.net/ubuntu/ttylinux-uec/ttylinux-uec-amd64-11.2_2.6.35-15_1.tar.gz
 
 # allow local overrides of env variables