Add some useful (for me) options - only-column-names and auto-create-csv

[dumbmatter]

Thanks for this program, it is useful. IMHO, it'd be a bit more useful with these two options :)

By default, the first three lines of output will describe the columns: labels, names, and formats, respecitively. To only output one line of header information containing just column names, use the --only-column-names or -o option:

./sas-convert/sas-convert -o <file.sas7bdat> [file.csv]

By default, if you don't pass the second argument, the output is sent to stdout. If instead you'd like to save it to an automatically named file based on the name of the input file, the --auto-create-csv or -a option will save this output to my-filename.csv:

./sas-convert/sas-convert -a my-filename.sas7bdat

[gijskant]

Thanks for your contribution!