0.9.0: Queueing lock

Breaking changes

• Rename PostgresConnector into AiopgConnector (#225):

  The class PostgresConnector became AiopgConnector. The only change is the name.

Migrations

• https://github.com/peopledoc/procrastinate/blob/0.9.0/procrastinate/sql/migrations/delta_0.8.1_001_add_queueing_lock_column.sql

Features

• Add notion of "queueing lock" (#219):

  Queueing locks can ensure periodic jobs do not accumulate in the queue: at any given time, only a single job with a given queueing lock can be waiting.

  See https://procrastinate.readthedocs.io/en/latest/howto/cron.html#launch-a-task-periodically

Documentation

• Fix PostgreSQL docker example in quickstart doc (#230) (Thanks @tmartinfr!)

Miscellaneous

• Code improvements around Procrastinate Admin module (#224)