Log Message:
Update ruby-addressable to 2.5.0.

# Addressable 2.5.0
- dropping support for Ruby 1.9
- adding support for Ruby 2.4 preview
- add support for public suffixes and tld; first runtime dependency
- hostname escaping should match RFC; underscores in hostnames no longer escaped
- paths beginning with // and missing an authority are now considered invalid
- validation now also takes place after setting a path
- handle backslashes in authority more like a browser for `heuristic_parse`
- unescaped backslashes in host now raise an `InvalidURIError`
- `merge!`, `join!`, `omit!` and `normalize!` don't disable deferred validation
- `heuristic_parse` now trims whitespace before parsing
- host parts longer than 63 bytes will be ignored and not passed to libidn
- normalized values always encoded as UTF-8