Small bug (improvement suggestion) in the quickstart doc

[jnboehm]

Reading through the quickstart, the variable jpeg_quality is not defined explicitly. Since the RGBField uses the raw write mode in that example (as it's the default), I think it'd make more sense to remove the jpeg_quality argument from the code snippet to make things easier to grasp at the beginning.

[andrewilyas]

Fixed! 6c3be0c