Added csv to binary classifier training data utility.

Hi John,
Wrote this general purpose tool last night while learning vw. Here's a link to the full example for some more context:  https://github.com/ericwhyne/vowpal_wabbit_binary_svm_example

Eric

Ariel,
I just updated this pull request with your recommended changes.
Renamed file
Added examples
Added more elegant option parsing
Added stdin and stdout functionality

R/
Eric