New plants

The last PR got slightly messed up due to Git being weird for me.

![newplants1](https://cloud.githubusercontent.com/assets/7812993/3917210/51c25960-2388-11e4-916c-da590f271246.PNG)![singulopotato_animation](https://cloud.githubusercontent.com/assets/7812993/3917251/07476a96-2389-11e4-90dc-320cc6ea64d6.gif)
(Animation is rewinded ingame so it looks better, I promise!)

*Adds the singularity potato. You can crush it in your hand to create a vortex like effect that will pull in nearby moveable objects and mobs. Range and lenght of stun depend on potency. Max is 7 range and 3 ticks stun. Has adminlogging support.


*Adds the spiderplant. It yields spiderpods which you can open for a small chance to spawn a spiderling. Chance of spawning depends on potency and is only 60% even at potency 100. You can also cut it with a knife to get spidermeat for cooking or grinding into reagents as the pods contain one of 5 randomized poisons. Has adminlogging support.

*Changes the sprite of the potato seedpack. It now has a potato on it instead of just a P.
![potatoseed](https://cloud.githubusercontent.com/assets/7812993/3917263/32f04bcc-2389-11e4-90ab-f9a7e784aa2b.png)

*Blood tomatoes will now spawn gibs instead of just blood if the tomato potency is at 50 or higher!

![bloodtomatonew](https://cloud.githubusercontent.com/assets/7812993/3917219/6dc7d1b2-2388-11e4-96ce-7a725dd9972b.PNG)
(I used two blood tomatoes here to demonstrate the difference between less than 50 potency and more than 50 potency potatoes.)

This has been tested and should be mergeable!