Added padding and fixed a nasty bug on multi page spawned band

Added padding as option to band (the same as border, wrap, etc) and fixed a nasty bug that made very long bands explode if a row "gapped" on a new page. 

Sorry for the "commit river" as I rolled back to your version before asking for merge. I suggest updating package.json with new pdfkit version as well, as you can see in my "for_air" branch