Repository object emitter - notify done

[marcolarosa]

in the filesystem method:

https://github.com/CoEDL/ocfl-js/blob/master/lib/repository.js#L176-L202

In this method (filesystem), at the end of the for loop (line 181 for (let d of dirs)), if root === this.ocflRoot then emit done:

this.emit('done')

In the S3 method emit done when walk = false (https://github.com/CoEDL/ocfl-js/blob/master/lib/repository.js#L218)

[moisbo]

Hi Marco -- please check #10