unescape path on commonlogger

### Problem
`Rack::File` unescape the file path, https://github.com/rack/rack/blob/master/lib/rack/file.rb#L41 , So the middleware that is setting that up is suppose to escape it, for instance on rails https://github.com/rails/rails/blob/master/actionpack/lib/action_dispatch/middleware/static.rb#L24 .

The problem is, that the logger, doesn't unescape, and end up showing this log:
```
"GET %2Ffavicon.ico HTTP/1.1"
```

### Solution
call unescape before logging it.

[ref rails/rails#11816]
We should catch encoding exceptions here, otherwise this could be abused to prevent evil requests from reaching the logs.