Create MIME type tests about edge

[wthorp]

If someone uploads something with [gateway-mt, linksharing, uplink] does the content/type get set correctly in [gateway-mt, linksharing, uplink]? What if the type is not set, can it be guessed from file extension? We think that Gateway-MT does not guess the content type, but linksharing does. What does Amazon do? -MT should if Amazon does for sure.

[halkyon]

AWS CLI does guess the type when uploading a file, although it's conceivable it could get that wrong if you don't have the mime types loaded somewhere on your machine (e.g. /etc/mime.types). You can also disable guessing with --no-guess-mime-type, or set --content-type to whatever you want to override any guesses. Storj S3 gateway and AWS S3 will set binary/octet-stream as a default if nothing was sent from the client. S3 SDKs will send application/octet-stream as a default if no ContentType parameter was set when uploading an object, so it's all highly dependent on the client.

It looks like we're doing what S3 does.

I'll look at documenting the above for gateway somewhere.