Add simple channel I/O using Cstruct.ts and capable of using SSL

Signed-off-by: David Scott <dave.scott@eu.citrix.com>
Add unbuffered Cohttp IO module

We need to perform an HTTP transaction without reading too much
data, so we can pass the file descriptor to another process without
stealing any of its data.

Signed-off-by: David Scott <dave.scott@eu.citrix.com>
Add Disk.{to_uri,start_upload} which use the XenServer import_raw_vdi interface

Signed-off-by: David Scott <dave.scott@eu.citrix.com>
lwt example: upload_disk

Add the ability to create a target VDI in the Pool's default
SR.

Signed-off-by: David Scott <dave.scott@eu.citrix.com>
lwt test: upload_disk now can upload the disk contents

Signed-off-by: David Scott <dave.scott@eu.citrix.com>
Update _oasis to have new disk import code

Signed-off-by: David Scott <dave.scott@eu.citrix.com>
Regenerate OASIS

Signed-off-by: David Scott <dave.scott@eu.citrix.com>
Merge pull request #11 from djs55/import_raw_vdi

Add support for disk uploads