Is there is a way for me to copy/back up me Google Drive contents to my local machine?
Ideally, the solution would have these features (in order of priority):
Runs on OS X/Linux in a headless (CLI/command-line) way, so it can be easily automated.
Converts the Google Docs files to MS Office/OpenOffice equivalents during the backup (currently, the Google Drive client does not synchronise the content offline in a way that can be usefully used without Google Docs).
Backs up all documents, not just the non-Google Docs ones.
Performs a "delta" backup, pulling down only the changes since the last backup.