Read and write as required, name and closed properties added, xreadlines fixed - a significant increase in tests

I am putting python-s3file into ftp-s3 so that that has write capabilities. It needs a couple of the file like properties. I am overwriting some fairly large files so I have made the read and write lazy so that I am not writing data that has not changed and not fetching data that I intend to overwrite.

Hope you find this useful.