Schedule reindexing on task queue if on GAE
Task model
Task model and migration
Development snapshot
Added missing session commit() to task
Fixed issues with tasks not being set to run, filter amount of results shown
Show rows with warnings errors or messages
Pass cookie header to TaskQueue
Flash notifications for import status reporting
Merge remote-tracking branch 'origin/develop' into feature/task_queue
No flash msg on cancel button
Reindex task now works without deferred task
Peopole import now works without deferred task
Export people background task
Showing all rows in import people preview
Add `db.rollback` so unintended changes don't persist

* Previously, "import preview" / "preview dry-run" would actually save
  some changes to the database.
Removed line-ending whitespace
Added queue.yaml.dist, tasks no longer using default queue
Only admin should be able to access /tasks/* urls
Check size of pickeled fields and compress content