add an upload endpoint

Thanks for this great project.
It would come handy having an upload endpoint, I forked the project and added one based on the base flask example but my react skills are close to none so I don't find it worth of a pull request, so, what about including one? I'm thinking on the scenario when we profile a remote host and want to upload the results directly to our application running in our workstation.

[mmarchini]

An upload endpoint is probably a good idea. I would rather have it as upload -> process -> return flamegraph instead of saving the file to disk. Not sure what others think.

Would that mean adding the option to process whatever you send through that endpoint or changing the way the application works currently? I went for the upload and save locally because that meant upload, save and don't worry on keeping track on what's been uploaded because it is in the "examples" directory and that is already listed, so redirect to /# will have it listed when the page loads. It would be interesting to have both options, but probably that's more effort than people would want to invest in a part that is not core functionality (?).
Thank you @mmarchini for listening to my suggestion.