Added meta value attribute for increased help file verbosity

I really like the meta value concept as described here: http://docs.python.org/2/library/argparse.html#module-argparse

It displays a short string in the option list which better ties the inputs with the helptext. For example:

--file=FILE             Uploads the file FILE to the remote server
-n INT                   Repeats the action N times (must be an INT)