Update package.json

In addition to adding a bug fix with no API impact, I just bumped the netpbm module to 1.0.0. Updating your dependencies so that you'll get the benefit of that bug fix and future improvements without any bc issues (~1.0.0). Thanks for using netpbm in your project!
Merge pull request #1 from boutell/patch-1

Update package.json to netpbm 1.0.0