Combat improvements

[Cappo66]

• cooldown on grenades
• add some kind of statistics so people could see how many kills / arrests they got (on F1 f.e.)
• people die whenever they get hit by a helicopter's perk... could be a good idea to remove that, as it might be easily abused
• add hospital spawn protection (like 15 seconds, during which people could spawn a car by a disk without getting arrested)
• jail needs some improvements (wouldn't be a bad idea to move it somewhere else)