Uses images_path instead of generated_images_path

[calumbrodie]

It would be better to use the variable 'generated_images_path' rather than just 'images_path' when saving the png.

Seems more correct as per the intentions of the compass configuration... http://compass-style.org/help/tutorials/configuration-reference/

[aaronrussell]

You're right, although I think that config variable didn't exist when this plugin was created (before Compass had all the sprite stuff in it).

Happy to take a pull request, if not I'll leave this ticket open and can hopefully make the change when I do another OSS day.

[calumbrodie]

I'll try and knock up a PR. In order to not break BC I'll check to see if 'generated_images_path' is set, and if not fall back to 'images_path'.