Prepare release 2.1.0

Remove default_app_config configuration

enable use of replica database

When you use replica database the django-auditlog try to write in the same database where object was read (replica). But this is a read only database and crash the application.

This changes saves always in the default database.

If you want to save in multiple databases or in a special one use `DATABASE_ROUTERS` to configure it.

build: explicit the build system

Setuptools is needed to build this package.

Review improvements

Bump version

Remove multi-db tests to make them more reliable

Fixes jazzband#213

Fix deploy config

* Bump version

* Set pypi config in .travis.yml

Merge pull request jazzband#160 from jjkester/v0.4.5

v0.4.5

Merge pull request jazzband#150 from jjkester/v0.4.4

Version 0.4.4