Reverted Bozar's firing sound change, as it's still a machine gun

(closes #333)

History:
* Per suggested sound swap with M60 in his walkthrough.
* Seraph implemented it in his patch mod.
* killap took Seraph's patch as the base of UP/RP.
* In RP 2.2+ the modified Bozar proto was not included, but still in UP.
* The proto got synced back to RPU from UPU.

Author: NovaRain