Ability to disable spellcheck for text edit fields

[f0x52]

I think in a lot of JSON models spellchecking the values does not really make sense.
This can be disabled for textareas by setting the spellcheck="false" attribute.

From a quick look at the source I couldn't really find a good place to insert that additional prop, would you be able to provide a (global) option for setting this?

[CarlosNZ]

Thanks for the suggestion @f0x52 -- I'll look into the best way to make this available.