Support for public boards
Support for public boards

I didn't see support for accessing public boards with this api. (e.g., https://api.trello.com/1/boards/4d5ea62fd76aa1136000000c?key=158f77ec277ade783377b02ea80c3741).

Added some small changes so that tokens are now not required, and if it's not provided, it will attempt to open a public board with that ID.
mehdy/py-trello,ntrepid8/py-trello,gchp/py-trello,WoLpH/py-trello,nMustaki/py-trello,sarumont/py-trello,Wooble/py-trello,portante/py-trello,merlinpatt/py-trello