Use the xenstore path convention from libxenvchan.h

This is a backwards-incompatible change. Rather than allowing the
user a free-form path in xenstore, instead a user must supply a remote
domid (int) and a port (string).

Signed-off-by: David Scott <dave.scott@citrix.com>
Use an abstract type Vchan.Port.t instead of a string

This is another backwards-incompatible change. This prevents the user
accidentally providing an invalid port (which must be a valid xenstore
path element)

Signed-off-by: David Scott <dave.scott@citrix.com>
Bump version to 2.0.0 (backwards incompatible) and update CHANGES

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

Signed-off-by: David Scott <dave.scott@citrix.com>
Merge pull request #22 from djs55/use-recommended-paths

Use the recommended xenstore paths in the interface