add utf8 test

```
failures:
---- utf8_router stdout ---- 
        task 'utf8_router' failed at 'index 4 and/or 17 in `고양이/여기!` do not lie on character boundary', /home/rustbuild/src/rust-buildbot/slave/nightly-linux/build/src/libcore/str.rs:1834
failures:
    utf8_router
test result: FAILED. 17 passed; 1 failed; 4 ignored; 0 measured
```