[data-viz] add design version

- Add raphael-min.js
- Add require to raphael
- raphael_overlay.js :
 - create rectangle according to model
 - generate random positions
 - add link between object
 - open a specific model
 - glow on current object and relation

- Change routes.rb :
  - now the data model display is accessible on /display_data_viz route

- Save json file :
  - add 3D button to save positions
  - create the folder /files/data_viz to store the position files
  - create the file
  - check if a position file exist and take the right positions