leaflet 8.x-1.0-beta2

Added explicit dependency from the Goefield module, both in the composer.json and in the info.yml file
Major Module code Refactoring of all the code base to:

• comply to PHP Drupal Coding Standards
• use Services & Symfony Container
• implement Dependency Injections

Improvement of the UI
Better and Updated Readme.md documentation
Embedding of Leaflet Library (v. 1.0.) files into the module itself.