Update lerna

[thibautRe]

Overview

This PR aims to use lerna script utils instead of the home-made script that we developed when launching the project.

Instead of using our script, we can now use lerna exec -- babel src -d lib to compile everything.

Some other changes include :

• Add src/index.js file for fyndiq-styles-fonts, mainly to enable the new compile flow.
• Remove the homemade identity proxy object, replaced with identity-obj-proxy
• Use rimraf instead of rm -rf. Less prone to error.

How to test

• npm run clean to remove all the compiled files
• npm run build to build the files
• npm run dev to build and watch the files, and run the storybook.

[Frinsh]

+1