Move project to accounts app

[txels]

This looks like a lot of changes, but it's only the result of moving Project to the accounts app.

I for now squashed all migrations into one per app. At some point we can decide that the models are stable enough, or we have enough local test data that we want to start properly migrating stuff. Until then we can use schemamigration --auto --update.

[alexcouper]

Squashing all migrations makes a lot of sense to me.