Function Fatal

It would be useful to add functions:

    func (c *T) Fatal(args ...interface{})
    func (c *T) Fatalf(format string, args ...interface{})

like in package testing (http://golang.org/pkg/testing/#T)

I know that function "(*T).FailNow()" makes not sense in gotask so those funtcions would be the same than Error and Errorf.

So, you can build scripts just like if you were using package testing.