Travis CI: site documentation update at 2014-01-21 08:12:39 UTC.

Commit: https://github.com/urho3d/Urho3D/commit/48eb0497df20f0a3c3a94ca96b19b12d4976904b

Message: Rename var name from <package>_INCLUDE_DIR to <package>_INCLUDE_DIRS.

See http://urho3d.prophpbb.com/topic9.html.