Implementing docopt for argument parsing

Docopt is a great way to bring in the file arguments. The usage docblock
at the begining defines the arguments.
Fixing Excel time calculation

I verified this with our data and a remote date calculator. It still
requires a bit more verification to see if I'm getting everything right
about the Campbell Scientific date string and the Excel information
Removing hard coded file names

The filenames now get pulled in via docopt

Also adding some code to strip out the header information.