Update NContent.java

Fixes error message form forestry:

    2013-06-14 02:54:57 [INFO] [Forestry] Received an invalid 'add-farmable-crop' request 'farmWheat@12659.0.3260.3farmWheat@12659.1.3260.8' from mod Natura.
Update NContent.java

Fixed Killen derp.
Merge pull request #17 from ScottKillen/master

Fixes IMC error message from forestry: