Fixed csv header names

Changed header names to be more readable
Just realised it would be better to actually move some of this logic to the DecisionType class, e.g. add a method name_for_display that would do the matching; and also perhaps use a regular expression for this matching? something like /^i+\) /should probably cover them all.
We would still need the method in eu_decision, but perhaps rename it to 'decision_type_for_display'.