Add -d option to make source maps work in Chrome/Firefox.

From documentation (npx webpack --help):
  -d           shortcut for --debug --devtool eval-cheap-module-source-map --output-pathinfo

Rationale: There is already an eslint config in this repo.
Adding eslint as a dependency means that developers do not need
to install it globally and everybody is using the same version.

Add `originalSize` option, which allows to display a downscaled version of the
image in the cropping interface, but use the original size for crop attributes.

Add originalSize option