Ignore .babelrc when publishing

[ryb73]

This causes problems when using webpack to compile a project which is dependent on react-draggable-list. It tries using the .babelrc but AFAICT that's not necessary because the source was already transpiled before being published.

[Macil]

Genuine thanks for looking to improve the project, but I'm inclined to follow redux-optimist's lead here.

I don't want to take this as there are other reasons running babel against node_modules will break things and merging this encourages people to think it's a good idea to do so. I also don't want to have to make the same change to all my other packages or leave all the other module authors in the position of having to do the same thing.

Users shouldn't be transpiling pre-transpiled files under node_modules. Failing fast like this lets users know they're doing something wrong.