Log Message:
Update databases/py-peewee to 2.8.3.

Bugs fixed and general changes

- #1028 - allow the ensure_join method to accept on and join_type
  parameters. Thanks @paulbooth.
- #1032 - fix bug related to coercing model instances to database
  parameters when the model's primary key is a foreign key.
- #1035 - fix bug introduced in 2.8.2, where I had added some
  logic to try and restrict the base Model class from being
  treated as a "real" Model.
- #1039 - update documentation to clarify that lists or tuples are
  acceptable values when specifying SQLite PRAGMA statements.
- #1041 - PyPy user was unable to install Peewee. (Who in their
  right mind would ever use PyPy?!) Bug was fixed by removing the
  pre-generated C files from the distribution.
- #1043 - fix bug where the speedups C extension was not calling
  the correct model initialization method, resulting in model
  instances returned as results of a query having their dirty flag
  incorrectly set.
- #1048 - similar to #1043, add logic to ensure that fields with
  default values are considered dirty when instantiating the
  model.
- #1049 - update URL to APSW.
- Fixed unreported bug regarding TimestampField with zero values
  reporting the incorrect datetime.

New stuff

- djpeewee extension module now works with Django 1.9.
- TimestampField is now an officially documented field.
- #1050 - use the db_column of a ForeignKeyField for the name of
  the ObjectIdDescriptor, except when the db_column and field name
  are the same, in which case the ID descriptor will be named
  <field_name>_id.