Avoid passing in large (sparse) vdi_info structs as arguments

We will prefer being explicit about which arguments are actually
required.

Signed-off-by: David Scott <dave.scott@citrix.com>
Incremental commit of the cmdliner interface

Signed-off-by: David Scott <dave.scott@citrix.com>
ocaml: add dependency on cmdliner

Signed-off-by: David Scott <dave.scott@citrix.com>
Hand write a parser and printer for string * string lists

Signed-off-by: David Scott <dave.scott@citrix.com>
Merge pull request #1 from djs55/cmdliner

Cmdliner