added some todo comments on areas that need further investigation
added an IWidget interface definition
Merge remote-tracking branch 'refs/remotes/upstream/master' into widget-refactor
Removed DS_Store files and added a .gitignore that ignores them in the future (as well as some other things)
replaced removed d3.last w/ array.reduce and removed helper method compareLen
Merge pull request #8 from mlippert/widget-refactor

replace d3.last, add .gitignore, initial IWidget interface
removed unusued widgets.js call