Generalize data script

[olafveerman]

All the census data provided on http://censos.ine.pt/xportal/xmain?xpid=CENSOS&xpgid=censos_quadros seem to follow the same structure. It's a zipped XLSX, with consistent naming of file + sheets.

We could make the first script more general so it can handle all the files. The user should only have to put in the number of the issue to be processed (eg. Q605, Q101)

The user could pass an option at what geographic level the data should be aggregated. If none specified, it will do it all.

[olafveerman]

Only totals will be included in the first version, none of the other columns that further specify the result.

[olafveerman]

Most of the generalization has been done and included in #7

Spinning of the different admin areas to another issue -> #8