Cycles: Fix unreported - Missing node group for the Camera Node

Thanks to linda2 for reporting in IRC.

intern/cycles/render/nodes.h

@@ -770,6 +770,7 @@ class CameraNode : public ShaderNode {
 public:
 	SHADER_NODE_CLASS(CameraNode)
 	bool has_spatial_varying() { return true; }
+	virtual int get_group() { return NODE_GROUP_LEVEL_2; }
 };
 
 class FresnelNode : public ShaderNode {