replaces babel compact with babel preset minify for better minification information (fix for issue #73)

[mbehzad]

babel compact mainly removes unnecessary white spaces and new lines docs, babel minify preset has a more aggressive minificiation options. which would result to a better file size calculation.

using devtool option from the webpack build with inline source map or eval would lead to a bundle not suitable for minification, or for production. a recommendation block is added which tells the user when wrong devtool option for the sourceMap was used for the production build.