Added ability to add due date to cards added to Trello

Add the due date to the card to be added to the Trello board.
Format to add the due date is in MM/DD/YYYY format.

For example :

trello Alfred Workflows; Are Awesome!; 09/02/2014

will add a Trello card with Title "Alfred Workflows", with Description "Are Awesome!", and with due date set as Sep 02, 2014.