Attachments support

[hellboy81]

is there possible to upload attachments simultaneously with documents setup ?

[cliffano]

At the moment there's no attachment support, but that would be a nice feature to add.
Development hints:

• have a look at nano's multipart and attachment functions https://github.com/dscape/nano
• attachments can be added to Couchpenter configuration, a property with array value pointing to file paths. this needs to be a special property that doesn't get added to the document (e.g. _attachments), use async to upload multiple attachments in parallel
• modify lib/db.js #createDocuments to handle the _attachments property accordingly
• make sure build passes (npm install -g bob && bob build, otherwise Travis will do the job post-commit)

However, I'm currently not working on any CouchDB-related project, so this will unfortunately be very low on my todo list. Pull requests are welcome.