Add Grunt build. Remove Require

This has Grunt produce a d3-financial-components.js file of all the component code which is copied to _dependencies for the examples to use. There are also tasks for jshint and jscs. Could add minification / watch task.
Require js has been removed, but I've kept a module pattern. We might not need this if everything is namespaced.
We'll need to think about inter-component dependencies - the only one at the moment is financescale depending on weekday, but there may be more in future.