Add audio-file upload and capabilities endpoints

[willemarcel]

Resolves #37

@sunu we need to add those environment variables to the API container:

MINIO_SERVER_URL='storage.googleapis.com'
MINIO_BUCKET_NAME='bioacoustics-devseed-staging'
MINIO_BUCKET_LOCATION='us-central1'
MINIO_ACCESS_KEY
MINIO_SECRET_KEY

The server url should not contain https:// or http:// prefix.