Log Message:
Update databases/py-peewee to 2.8.2.

Bugs fixed and general cleanups
- fixed some bugs related to the Cython extension build process.
- allow blanks and perform type conversion when using the db_url
  extension
- added the ability to query using the <foreign_key>_id attribute.
- ensure that peewee.OperationalError is raised consistently when
  using the RetryOperationalError mixin.
- ensure that pwiz will import the appropriate extensions when
  vendor-specific fields are used.
- ensure that pwiz-generated models containing UnknownField
  placeholders do not blow up when you instantiate them.
- correctly limit the length of automatically-generated index
  names.
- fixed bug where BlobField could not be used if it's parent model
  pointed to an uninitialized database Proxy.
- greater consistency with the conversion to Python data-types
  when performing aggregations, annotations, or calling scalar().
- ensure the correct data-types are used when initializing a
  connection pool.
- fix bug where Signal subclasses were not returning rows affected
  on save.
- added documentation about SQLite limits and how they affect
  insert_many.
- better warnings regarding C extension compilation, thanks
  @dhaase-de.
- fix bug where table names starting with numbers generated
  invalid table names when using pwiz.
- fix bug where parameter was not being used. Thanks @jberkel.
- fixed the way SqliteExtDatabase handles the automatic rowid (and
  docid) columns. Thanks for alerting me to the issue and
  providing a failing test case @jberkel.
- fix obscure bug relating to cloning foreign key fields twice.
- allow set instances to be used on the right-hand side of IN
  exprs.
- fix behavior where the default id primary key was inherited
  regardless. When users would inadvertently include it in their
  queries, it would use the table alias of it's parent class.
- add support for db_column in djpeewee
- fix the behavior of truncate_date with Postgresql. Thanks
  @Zverik.
- allow DATABASE_URL as a recognized parameter to the Flask
  config.
- correctly handle bytes wrapper used by PasswordField to bytes.
- when selecting and joining on multiple models, do not create
  model instances when the foreign key is NULL.
- do not coerce the return value of function calls to COUNT or
  SUM, since the python driver will already give us the right
  Python value.
- use global state to resolve DeferredRelations, allowing for a
  nicer API. Thanks @brenguyen711.
- attempt to avoid creating invalid Python when using pwiz with
  MySQL database columns containing spaces. Yes, fucking spaces.
- fix bug in SQLite migrator which had a naive approach to fixing
  indexes.
- explicitly check for None when determining if the database has
  been set on ModelOptions. Thanks @joeyespo.

New stuff
- Added TimestampField for storing datetimes using integers.
  Greater than second delay is possible through exponentiation.
- Added Database.drop_index() method.
- Added a max_depth parameter to the model_to_dict function in the
  playhouse.shortcuts extension module.
- SelectQuery.first() function accepts a parameter n which applies
  a limit to the query and returns the first row.
- group_by(), order_by(), window() now accept a keyward argument
  extend, which, when set to True, will append to the existing
  values rather than overwriting them.
- Query results support negative indexing.
- C sources are included now as part of the package. I think they
  should be able to compile for python 2 or 3, on linux or
  windows...but not positive.