exploit fix, electric boogaloo : canister edition

https://github.com/Baystation12/Baystation12/commit/024a0baa49df0cb1ec8af4967fefe9d5575453eb removed the exploit protection of canisters without replacement, this commit fixes that.

without this, anybody can open/close valves and all other forms of messing with any canister from anywhere.

ALWAYS keep in mind, NanoUI will update the fancy buttons CLIENTSIDE, that does NOT protect against exploits !

the actual buttonpush can still be spoofed to the server even if NanoUI disabled/hid/greyed-out/removed the button !
Conflicts:
	code/game/machinery/atmoalter/canister.dm
Fixes human flag
Merge pull request #161 from ZomgPonies/master

26/05/14 - 3