Merge pull request #86 from kbarber/maint/master/pin_postgresql_fixtures_to_250

Pin fixtures to use postgresql 2.5.0
Release 2.0.0

This modifies the CHANGELOG for the 2.0.0 release, and adds an upgrading
section to warn users about the `inifile` change during the upgrade.

Signed-off-by: Ken Barber <ken@bob.sh>