Add ability to list distros/versions with 'downburst list'

It looks at all the images on the web-server from ceph.com for
non-ubuntu distro's and the ubuntu cloud server and figures out
all available distributions/versions that can be used by downburst
and prints it in a readable way.

Signed-off-by: Sandon Van Ness <sandon@inktank.com>
Increased comments and comment formatting.

Signed-off-by: Sandon Van Ness <sandon@inktank.com>
Allow use of release/codename for Ubuntu.

Signed-off-by: Sandon Van Ness <sandon@inktank.com>
Use HTML parser/Fix typo.

Use HTML parser instead of manually parsing. Fix typo
in release names/versions.
Signed-off-by: Sandon Van Ness <sandon@inktank.com>
Allow codename instead of version for Ubuntu.

Let distroversion take a codename like quantal instead of
the version IE 12.10.


Signed-off-by: Sandon Van Ness <sandon@inktank.com>
Allow use of raw images denoted by .raw extension

Allow downburst to use raw disk images instead of our
normal compressed qcow2 images (for better performance).

The raw images are detected/set by their file-extension
which is .raw instead of .img.

Signed-off-by: Sandon Van Ness <sandon@inktank.com>
Added codename/release shown for ubuntu in 'list' command.

Made it so the codename/release is also shown for ubuntu when
listing available distributions.

I also removed unused stuff.

Signed-off-by: Sandon Van Ness <sandon@inktank.com>
Merge pull request #7 from ceph/wip-list-distros

Add ability to list distros/versions with 'downburst list'