Ddo

Results 3 issues of Ddo

``` setex(test, 5, 'test val') get(test) > 'test val' # delay 5s get(test) > null keys() > test ```

bug
good first issue

I can't find any API page anywhere? The API on the README file is 404 https://github.com/readium/readium-js/blob/master/API.md?plain=1#L56

- [x] dlog.Error - [x] default Rq - [x] readme - [x] godoc - [x] export/import - [x] semaphore - [x] default transport - [x] check multiple header values -...