Allowing passing useGriddleStyles={false}

[0xdabbad00]

I need to disable the griddle styles for two reasons:

• Mine are prettier :)
• I use Content-Security-Policy:default-src 'self' which denies any inline style sheet setting.

For now, I have just copied griddleWithCallback.jsx to my project and added useGriddleStyles={false} to https://github.com/DynamicTyped/GriddleWithCallback/blob/master/scripts/griddleWithCallback.jsx#L190

[0xdabbad00]

Just realized this can get passed through, so no change needed, but I'll leave this open just so you can consider the Content-Security-Policy issue.