Polluting node_modules with unnecessary files

[JuhQ]

The project pollutes any node_modules folder with unnecessary files.

Folders, such as examples, live-demo and build/images should not be bundled in with the npm release.
As mentioned in #14, react itself should be peer/dev dependency, therefore we could get rid of the unnecessary node_modules folder as well.

As package.json defines the main entry point as build/AddToHomeScreen.js, I would also propose src folder not to be bundled with the release.