should enable to create implementation specific tests

[hablutzel1]

Basically the flow could be this one:

From an implementation: press create tests button, select the implemented interface that contains the @should tags in its operations, then @should tags would appear as normally and the user could choose for which one to create the tests

@see http://elespaciodejaime.wordpress.com/2011/07/23/probando-la-interfaz-o-la-implementacion/