Volume handoff (fixes 17)

Fixes #17.
Decorate this with `@flocker_standard_options so that it gives correct version. Currently shows "Twisted" version.
```
$ flocker-volume acquire --help
Usage: flocker-volume [OPTIONS] acquire <owner-uuid> <name>
Options:
      --version  Display Twisted version and exit.
      --help     Display this help and exit.

```