Add xapi-xenopsd and the CLI

Signed-off-by: David Scott <dave.scott@eu.citrix.com>
xapi-xenopsd: add a patch to disable -warn-error

These pre-1.0 versions are pre-releases. I expect -warn-error to be
disabled for the 1.0.

Signed-off-by: David Scott <dave.scott@citrix.com>
Depend on obuild >= 0.1.1 for maximum portability

See #2744

Signed-off-by: David Scott <dave.scott@citrix.com>
xapi-xenopsd: dummy commit to trigger travis

Signed-off-by: David Scott <dave.scott@citrix.com>
xapi-xenopsd needs OCaml 4.01.0

Signed-off-by: David Scott <dave.scott@citrix.com>
message-switch.0.10.3 needs cohttp >= 0.10.0

Signed-off-by: David Scott <dave.scott@citrix.com>
Merge pull request #2744 from djs55/xapi-xenopsd

Add xapi-xenopsd and the CLI