Add fallbacks to webpack config.

[allanhortle]

resolve: {
        extensions: ['', '.jsx', '.js'],
        modulesDirectories: ['src', 'node_modules'],
        fallback: [
            path.resolve('./node_modules')
        ]
    },
    resolveLoader: {
        fallback: [
            path.resolve('./node_modules')
        ]
    },

Lets you dev with symlinks much better.