Fixed Supply Drop command for officers.

The Tactical Supply Drop command was removed from the game and was
merged with the Medical Supply Drop and then became Supply Drop.

The script can properly check if the actor has the tactical serum
expertise box or not.
Deleted another unused command script
Supply Drop now uses the correct crate
Fixed incorrect math (Healing Potency)

Healing Potency now functions properly.
Merge pull request #110 from Ziggeh/master

Fixed Healing Potency and cleaned up Supply Drop (officer)