Show STDOUT and STDERR during testing

---

In this example there are print-statements both in the code and in the test function.

examples/testing/nocapture/src/lib.rs

pub fn add(left: usize, right: usize) -> usize {
    println!("STDOUT In the application");
    eprintln!("STDERR In the application");
    left + right
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn it_works() {
        println!("STDOUT in the test");
        eprintln!("STDERR in the test");
        let result = add(2, 2);
        assert_eq!(result, 4);
    }
}

If we run cargo test we don't see any of this as the tester captures them.

If we run cargo test -- --nocapture then we'll see the output of all the 4 print-statements.