Improve the way we manage behaviors on structures

[ecarriou]

Improve the way we manage structures to be able to add behavior on them.

Examples:

• component.on('location.cities[0].street, value => {}) : add a behavior on a specific property of an element of a collection.

• component.on('location.cities.street, value => {})): add a behavior on a specific property of all elements of a collection.