Add router module.

1. make a router from pattern, do pre-validation work.
2. support regex matching.
3. introduce "fuzzy" mode, or called something else. let "/a/b/" to match
not only match "/a/b/", but also "/a/b" and "/a/b/c/d/.../n".
4. add match functions.
5. add some test cases to test making a router.