Add party to tests

[nbdavies]

The diff is looking messy, but here's the gist:

• Party for Scattering was left blank, except for partisan primaries (in which we have Democratic Scattering, Republican Scattering, etc.).
• For non-partisan races, people candidates (i.e. not Scattering) got party "NP", except as noted in Party Oddities in Source Files openelections/openelections-data-wi#49.
• For partisan races, people candidates' parties were looked up in Wisconsin Elections Commission summary PDFs for the corresponding election.
• In a couple instances, we had lines with party and lines without party split out into separate blocks with the same file name. 20001107__wi__general__ward is an example of this. Those no longer need to be separate blocks for the sake of feature test formatting, so that duplicate file heading was removed.