Chapps

- The v0.5.x version milestone represents the completion of the first
major iteration of feature development for CHAPPS. It can now limit
outbound transmissions based on quota and authorization, and it can
apply greylisting and SPF enforcement to inbound email.

- SPF headers are now prepended to all email flowing through an inbound
policy service which includes the SPF handler. This is to increase
co-operation with downstream tools such as DMARC enforcement and spam
filtering tools.

- An annotated version of the default CHAPPS configuration file
has been included in the install directory, in order to serve as
a form of documentation about config options.

- Consolidated how Redis handles are created for testing

- Fix bug in Greylisting-via-SPF which caused errors when
softfailing emails passed greylisting.

- Add some tests to ensure that the code referenced above is
exercised properly to expose regressions.

- Add new "mail sink" for integration tests, which in fact does not
sink the email but instead reflects it back to the test via a UDS,
enabling integration tests to inspect the contents of the emails
they send.

- Add inbound-flags-adapter code to SQLA adapters.

- Add tests for all inbound-flags-adapter classes.

- Sort out conflicts between SQLA tests; all can once again run at once.

- Refactor configuration stategy to avoid package-global config object.

- Added basic admin functions in CLI: initialize/update database schema,
change API config-flush password, perform config-flush (with option to
write to an alternate location).

- Added Greylisting & SPF enforcement management commands in CLI.

- Added Greylisting & SPF enforcement management routes to API,
including routes to set a domain's enforcement preference, and
others to clear a domain's enforcement option cache in Redis.

- added chapps.alembic.versions subpackage, because of course Alembic
cannot work without the version files

- added missing package data which prevented Alembic migrations
from functioning as expected

- Refactored elements of the adapter classes to reduce code duplication.

- Added Alembic to project to manage database migrations.

- Created as-of-0.4.12 base migration, and an update migration to
add new option flag columns.

- Added greylisting and SPF-checking option flags to **Domain** records.

- Updated greylisting and SPF policy tests to accommodate new flags.

- Created new inbound handler class hierarchy, encompassing SPF
and inbound multipolicy handler.

- Created new multipolicy inbound service which combines SPF and
Greylisting in one service.

- NB: pre-existing databases need special care during upgrade, see
[README](README.mddb-initialization)