New method - honesly_attempted? - added

Returns the same thing as AnswerSheet.honest?

Added however to allow call to map given an array of student objects
Re-defined colour? method
[d3.js]: First instance of using d3.js. Will replace flot-chart eventually

d3.js is the new graphing library we'd be using. It is more powerful
and makes it possible to produce the best graphic for given data (as opposed
to showing everything in terms of bar/pie charts etc )
Merge branch 'course'