As you can see in the image, there are no cycles hair rendering options (at least where they were in previous versions). Did they remove these options in 2.78 for some reason?
They are now located in the geometry panel under render settings:
These settings are not actually per particle system as the location in the particle panel would imply, they're actually per scene. So not only are you not able to adjust them per system, what settings you have will be ignored when the model is linked into another file. Where you would then need some other object with hair particles to be able to set them up locally!
By placing them under render settings, the above issues and confusion are solved.