500 on invalid attachment

[einzige]

@cantino fails with 500:
https://github.com/einzige/mavenlink/wiki/Attachments

"A server error has occurred. If this problem persists, please contact support@mavenlink.com."

Works with correct attachment:

~ ❯❯❯ curl --form "attachment[data]=@test.rb" --form "attachment[type]=post_attachment" "https://api.mavenlink.com/api/v1/attachments.json" -H "Authorization: Bearer ****"

But response is weird:

{"id":16515055}%

[cantino]

Yea, that response is strange. It's an attachment_id, which you can later pass to Expenses or Posts, but it looks like it's not using Brainstem presenters for some reason.