Bumping up openstack-xapi-plugins to Icehouse release
Configure for current environment by default
ocaml-libvirt: bump the release number to prefer our package

Note the backports in the patchqueue are all from master, so the
next upstream release should include them.

Signed-off-by: David Scott <dave.scott@citrix.com>
configure: Tidy up distribution-type dispatch

Signed-off-by: Euan Harris <euan.harris@citrix.com>
Merge pull request #450 from euanh/build-improvements

configure: Tidy up distribution-type dispatch
Merge pull request #445 from amesserl/openstack-plugins

Bumping up openstack-xapi-plugins to Icehouse release
Merge pull request #446 from BobBall/jessie-fix

Jessie fix
Add ocaml-ssl-devel dep to ocaml-cohttp