Bounty Hunter: Return Fire

Buff and command works, cools down and is modified by skill mods, (i.e.
from "Enforcer set")
Bounty Hunter: Take Cover & Armor Sprint

Registered commands, added buff and command scripts.
Buffs apply, needs further testing.
Merge pull request #139 from DAK-/master

Bounty Hunter: Return Fire, Take Cover & Armor Sprint