Take padding into account in sprite maps

Only briefly tested in default mode, but seems to work so far.
1.0.1 - bug fixes #37
Fix #44
fix #48
Output sprite css file to multiple locations

This allows the user to output the sprite file to multiple locations.

For instance, I have it set as `cssFile: ["css/sprites.scss", "scss/components/_sprites.scss"]`, allowing for a preview compatible CSS file, and an scss file which integrates with my Sass system. The first array item is submitted to the preview document.

Admittedly, it's a niche feature, but I find it very handy.
Update index.js
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Lodash loop on line 291, obey project conventions

Apologies!
Actually include lodash loop

That'll teach me to use the web editor.