Added support for fields in method `_create`.

Now you can specify the fields of the object.
If the object's class doesn't support a field, a warning is shown.
Implemented fields in method `newProject`.
Updated tests.
A little reword in `newProject` doc.
Added warnings check to `testNewProject`.

Now the test checks that all the required field `name` does not
throw an "unsupported field" warning.