Office Zombie Rework

The Office zombie wasn't a big threat, so I reworked him to be better at breaking your defence (I haven't rebalanced the levels yet though)

Video on rework: 

• Office Zombie now flings over the plant he hits (Except Tallnut)
• Office Zombie Speed 4 > 3
• Office Zombie Health 20 > 45
• Office Zombie Damage 1 > 2