Add xen-4.4 to path
Upgrade to xapi 1.9.52

Signed-off-by: Jon Ludlam <jonathan.ludlam@citrix.com>
Merge pull request #502 from jonludlam/xapi-1.9.52

Upgrade to xapi 1.9.52
Merge pull request #500 from BobBall/trusty-fix

Add xen-4.4 to path