Add self service dissaggregation min-wizard

[troyel]

As loosely discussed - a) we want self-service wizard for adding dissaggregations on step 5. Understand if this does not make it to the M&E seminar presentation.

b) Also on the improvement of showing what is inside of the override category combinations - it would be good to have 1 or two columns of metadata to the left of the overview. Where we could sort on type of dissagregations.

E.g. we do not want to dissaggregate people by constructed/rehabilitated so to implement metadata on the categories to indicate what their data-catagero is (e.g. individuals, infrastructure, methodology etc).

[adrianq]

We plan to do some improvements in this sense for the M&E seminar. See #53. Afterwards we can discuss any major change