Prevent errors with user info missing
Merge pull request #139 from hotosm/history_missing_user

Prevent errors with user info missing
Allow empty values for imagery, changeset and entities to map
Merge pull request #141 from hotosm/project_edit_empty_imagery

Allow empty values for imagery, changeset and entities to map
Locking task rows using FOR UPDATE
Merge pull request #154 from hotosm/concurrent_locks

Locking task rows using FOR UPDATE
pragma no cover
New DB model
Fixing tests
Use default for datetime columns
Re-adding comments
Improving project tasks.json
Layout for task history
Fixing stats
Merge pull request #158 from hotosm/tasks_history_simplified

Clean up of the DB Model
First round for a migration script.
Don't check for first user but for first admin user instead
Some adaptations