Consider lazy instantiation of component under test to make tests mock friendly

[MarceloRuiz]

Consider deferring the instantiation of the visual component under test to right before the RController is retrieved to operate in the UI. In this way, users will be able to configure mocks in the test method right until the rcontroller() method is called (the point that indicates the user want to actually operate on the UI).

The problem with the @before annotation in the init method is that this method gets called before methods in the test class annotated with @before are called.

A simple way to avoid this problem could be by removing the @before annotation from init modify its signature to allow Exceptions to be thrown (see issue 17 [https://github.com//issues/17]) and replacing the rcontroller() method to perform the lazy instantiation:

// @Before  removed    
public void init() throws Exception {
    // content unchanged
}

public final RController rcontroller() throws Exception {
    if (controller == null) {
        init();
    }
    return controller;
}