Add .dropboxignore directory to exclude folders without using selective sync

I have greatly enjoyed the "packrat" feature of Dropbox which keeps a versioned archive of all of my files. As a developer, this has saved me countless times, as I don't always remember to push changes to a repo. That said, I dread anytime I start a new javascript front-end development project that uses NPM. My computer's CPU goes crazy trying to keep track of the thousands of files in the "node_modules" folder of that project, and frankly I have never once cared to have that folder synced across my devices or saved to the cloud. It would seem that both my computer (and I can only imagine the Dropbox cloud infrastructure) would greatly benefit from not having to index and save those files. Please strongly consider adding a selective ignore feature.