Rejigged core.

-Made it 100x more user friendly. Credential generation is now
 done automatically when you use get or post.
-renamed trello-get and trello-post get and post
-get-lists now does the request for the lists rather than just
 returning the url for the request (much cleaner)
TO-DO: update docs
Updated README to reflect last commit
bump to 0.2.1-SNAPSHOT