[Documentation] Demo working with backbone DO NOT MERGE

[GuenoleK]

What was done here

• [x] Setting the navigate, back and start functions (Router initialization)
• [x] Setting the global link for a good backbone navigation on the application (Global link initialization)
• [x] Using of the updated components on the good way (button-back, menu)

  Where to look, what to do now

• Initialize the router : https://github.com/KleeGroup/focus-demo-app/blob/e6f6177825893e5191e4a65d483919b882d62091/app/initializer/scripts/router-initializer.js The initialization should look like this. You now have to import your Backbone dependency and a function : setNavigationFunctions which set the navigate, back and start functions
• Before, in the code, we used to do this import history from 'focus-core/history', then that history.navigate('#search/advanced', true) Now do this import {navigate} from 'focus-core/history', then that navigate('#search/advanced', true);. It will be the same for back and start (For start, please look here : https://github.com/KleeGroup/focus-demo-app/blob/d726e8d20cb6e77fdafb0f2842fef0fb346828e4/app/application.js)
• To finish, don't forget to check at how the button-back and the menu are now written in focus-components :
  • menu https://github.com/KleeGroup/focus-components/blob/develop/src/components/menu/index.js
  • button-back https://github.com/KleeGroup/focus-components/tree/develop/src/components/button-back

[pierr]

The main goal of this PR is to be used as documentation for all projects to upgrade their version of Focus core.

• In focus core, we no longer depend on Backbone, but we don't remove all our code inside the Router to not break compatibility with the projects.