adds initial sharing group structures [skip ci]
Merge branch 'develop' of https://github.com/MISP/MISP into develop
adds Organisation and Sharing group CRUD [skip CI]
 - updates message flashing with better color coding:
    red == error, yellow == warning, green == success
 - updates schema to include organisation and sharing_groups tables;
 - adds baked fixtures and test cases for newly added models;
Enforce access limitations baased on sharing group
adds share to specific server option [skip ci]
sharing groups fixes [skip ci]
 - exports obey sharing group
 - Organisation HABTM SharingGroup
 - event alerts and publishing consider sharing group
 - users can download attachments only if in correct sharing group
 - MISP bake template, to be used for new scaffolds
Unique organisations and sharing groups
 - remove old org field from views, still present in controllers since it'll
   break everything if removed
 - show sharing groups in event view
Add org back in views, but hidden
Set user org based on new organisation field. Ensures backware compatibility
save sharing group in EventsController::_add() [skip ci]
    - changed JSON Sharing Group format to match other models
Merge branch 'feature/sharing_groups' into develop