Protection.cs issues with absent behavior on pre-UO:R era

[Bohicatv]

Current behavior: Doesn't do anything if expansion flags are pre-aos.

Expected behavior: OnCast adds armor rating based on caster's skill (magery).

Functional Math > increase armor rating by (magery / 10) = 1-10 pts.
Duration Math > 6 seconds x magery / 5 = clamped at 6 sec to 120 sec.

[kamronbatman]

Correction, currently acts the same as UOR, lower disturb chance for 120s.