Feat/evap upload svc

* made some small improvements to evaporate provider.
* added some meat to the upload service.
* added some basic tests for upload service, other parts of upload not yet tested.

TODO:
* add in use of uuid in prefixing upload file name
* add in additional headers for content type and privacy
This also makes sense for audio, in case we want to offer easy download links, but we may not want this for images or other files.