Scrape 2018 observer data

[LanesGood]

The breakdown of observers per province should be compiled from the multiple sheets in the workbook found here:

https://docs.google.com/spreadsheets/d/1H6T57vHCOJfofok4fMRdQ2ViUbEGmt867N8uyBarpRw/edit?usp=sharing

While the 2018 data story requests only total observers per province, I suggest we add all data points per province for posterity.

[LanesGood]

This is now available in CSV. @olafveerman should this be uploaded as a separate file, or merged with the existing province CSV?

provinces-observers.csv.zip

[olafveerman]

@LanesGood In future, please open PRs to master so we can review.

Things to do:

1. document the source of the data and the meaning of the ambiguous columns in a Readme. I think we should do this for every year and have opened a ticket to track Readme #15
2. remove geoId, this will be tracked in provinces.csv
3. better column names (no spaces, no typos, consistent syntax). Eg. observersTotal, observersFemle, pollingStationsMale

[LanesGood]

@olafveerman OK, I've added the Readme and replaced this file in a new branch