Add .dropboxignore directory to exclude folders without using selective sync

This is what I had back from Dropbox support last month on this issue. Don't know whether the dev team took any notice, but I will keep pestering:
"Thank you for this feedback. We are always looking for user input when creating the next version of the Dropbox app.
Unfortunately, I do not have access to the exact roadmap and am not able to say whether or not there is a plan for a similar feature.
However, I think the idea makes a lot of sense and I will make sure your comments are passed along to our development team."