Provide an option to partition and format a volume on create

Add options to "cinder create" that allow a user to partition a volume
as well as format it with a filesystem.

We don't need to cover every possible FS or partition scheme but just pick
some of the most common (ext3/4, xfs)?

Options for partitioning can be provided via a set of basic partition schemes
that could be selected from (similar to Nova's flavors). Formatting options
could just be an option passed in via the create call.

"cinder list-partitions"
  uuid: "Linux-LVM"
  uuid: "Linux-Extended"
  ....

Formatting options would be limited to some basic commonly used FS's like
ext-3/4, xfs

So the "cinder create" call could look like:
"cinder create --partition <Linux-LVM-UUID> --format ext4 \
 --name my-formatted-vol 100"

We'd use the existing internal cinder attach mechanisms to attach the newly
created volume to the Cinder node, partition it and format it (similar to
how we deal with loading images to a bootable volume, or cloning etc).

The next step would be to add a mechanism to Nova's attach to allow
specification of a mount point and have the volume auto-mounted.