Also include "Deregistered" and "Lapsed (Third Party)" parties

For the candidate database we'd also like to include candidates from the
2010 election, and lots of those were in parties that are no longer
registered. This commit reintroduces them to the CSV file - they're easy
to filter out based on the "Registration status" column anyway.
Merge pull request #1 from mhl/gh-pages

Also include "Deregistered" and "Lapsed (Third Party)" parties
Add a PPC scraper for the Conservatives
Factor out getting the JSON directory
Move Conservative PPC JSON into a subdirectory
Add a scraper for Labour PPCs
Add scraped Labour PPC data
Factor out the writing of JSON to a constituency-based filename
Add a PPC scraper for the Liberal Democrats
Add scraped Liberal Democrat PPC data
Rename the Conservative PPC JSON files to be constituency-based
Remove unused imports