There are some situations when we need to make toJSON work in
different ways:
- Communication with server where relations may be reduced to resource_uri
- Template rendering where we need more information that the one we send to the server

Adding `{full: true}` to toJSON allows to avoid `includeInJSON` params and make a full
serialization of a model and its relations.

toJSON method will avoid relational configuration `includeInJSON` and `keyDestination`
in case option `full=true` is included when calling the method.

It encapsulates toJSON(full=true) functionality where
keyDestination is omitted

There are some situations when we need to make toJSON work in
different ways:
- Communication with server where relations may be reduced to resource_uri
- Template rendering where we need more information that the one we send to the server

Adding `{full: true}` to toJSON allows to avoid `includeInJSON` params and make a full
serialization of a model and its relations.

toJSON method will avoid relational configuration `includeInJSON` and `keyDestination`
in case option `full=true` is included when calling the method.

It encapsulates toJSON(full=true) functionality where
keyDestination is omitted

…lational into feature/full-toJSON

Conflicts:
	backbone-relational.js