Just comment out the using UnityEngine.Networking.NetworkSystem
statement where the error occurs. The class doesn't even need it. You
can also do the same for the using System.Security.Policy statement in
OvrAvatarSkinnedMeshPBSV2RenderComponent.cs.N...
I don't know about an exact barebones program like you describe, but it
should be pretty easy to whip together using the
CAPI:https://developer.oculus.com/doc/0.4.3-libovr/_o_v_r___c_a_p_i_8h.html
FYI, the demo is being made available today. No word on whether it will
have the Rift functionality built
in.https://www.unrealengine.com/blog/41-release-notes