Rework drop and pickup items feature

Refactored the drop/pickup items feature into functions, and added
conditions to prevent glitch where player is able to pickup item
multiple times by spamming the pickup action. Pickup action is now
removed automatically by the game engine when activated.
Modify gang player uid to use same id that is used by stats

The previous gang uid used to contain parts of the player's name. This
was meant mostly for testing, to be able to spawn multiple clients,
with same UID, and join gang.
Fix problem with picking up items that have 0 weight
Refactoring for the drop, give, and use item scripts to use functions

- Refactored into functions the logic for giving and using items
- Changed the way that keys are given so that it's more intuitive,
player now just clicks on the "give" button on the keychain item, and a
dialog pops up asking which vehicle he want to give keys for.
Disable the ring factory

Disable the ring factory as it is not serving any purporse. It was
actually being used by a few people to exploit money. It was allowing to
produce diamond rings for free.  Eventually we should give it a new
role, or delete it.
Change TeamSpeak address
Rework the way keys are dropped, and given to players

- Removed the old Keychain menu, you are now able to drop, and give keys
with the same user-interface flow as other items
- Changed the logic for mobile phone, so that you are able to drop it an
sell it, and it gets removed from your inventory appropriately (you
still get a free phone when you respawn)
Fix amount on dropped items not being synced, and item pickup spam exploit
Fix problem where amount of items was not set correctly when giving
Add open tractor to truck shop
Merge pull request #48 from micovery/money-exploit-fix

Rework of pickup, drop, and give items feature to fix money duping, and other fixes