Limit filesize upload, stop in mutex from connection continuing

[rslay]

Users who try to upload files larger than given limit should have the upload stop if it goes past a certain filesize.

Optimal solution is to check filesize before letting the user start uploading, but it may not be that straightforward since clients can lie. Got to stop the upload the second it passes the filesize limit

[rslay]

I think it might be fixed in the latest version, had to switch from mutex to busboy and handle packets a more manual way. Need to test.

[rslay]

When using nginx as a reverse proxy this continues to be an issue, but in testing environments the TCP connection is cut early by the server. This needs to be investigated further