Add SVG/PNG to Workbox configuration.

[LasaleFamine]

We should add SVG files on the glob path of Workbox:

polymer-skeleton/webpack.config.js

Line 66 in 6cc16b8

new WorkboxPlugin({

new WorkboxPlugin({
    globDirectory: outputPath,
    globPatterns: ['**/*.{html,js,css,svg,png}'],
    swDest: join(outputPath, 'sw.js')
 }),

[maxknee]

@LasaleFamine I would like to help out with this project. If possible can you assign to me?

[LasaleFamine]

Hi @maxknee, thank you for your interest. Just take this and open a PR, it's ok for me. Just don't forget to create the PR on the develop branch. Thank you!