A command to dump the live PopIt instance in a mongimport-able format
Don't include people who've changed constituency in the 'not sure' section

Previously, people would only have been excluded from the "not sure"
section on the constituency page if either they're marked as standing
again in that constituency, or they're marked as not standing anywhere -
it was missing people who we know are standing in a different
constituency.

Fixes #694
Add scraped and auto-cropped PPC images
Add the unknown person icon from TheyWorkForYou
Add more manual matches of new candidates against old
Update the submodule with scraped PPC data
WiP: display candidate images (ropey CSS)

We should have some designer time this week to look at making this
actually look good, so this is just Work-in-Progress.