Unity3D 5.3.4p5 (patch version ***) and Beta version 5.4.0b16 both released on 27th April 2016 now include Oculus OVRPlugin version 1.3.2 for compatibility with Oculus Home/CV1 and work fine with DK2.
In both cases there is no need now to add in the OVR Plugin from the Oculus downloads page.
*** For those producing multiple delivery versions of their Unity projects remember that patch versions (like 5.3.4p5) of the current stable release (5.3.4f1) do not allow you to build and distribute a web player version of a Unity project as the web player is not globally updated until the next full release. Also remember that web player is to be removed from Unity 5.4 onwards. The current beta versions of Unity 5.4 do not include web player build support... WebGL being the replacement you might want to experiment with.