[feature request] Attachments

[itschip]

Adding support for uploading attachments to models which support it.

I haven't gone through everything in #38, so correct just close this if you have/are planning to add support for it.

Open to doing this myself and PR it if its not on your todo right now

[adamdotdevin]

attachments were already supported prior to the rewrite, we'll get them added back soon!

[rekram1-node]

closing since these are supported now