Initial working version with ORM and ODM support.

Still some refactoring to do, but the basic idea is working when
switching between the ORM and ODM drivers.
Oops...needed to validate composer.
Rename ORM fixture class.
Add a getAnnouncementManager() convenience method.

Replaces the repository service defintion.
Remove generated DefaultController
Define all config with XML. Config cleanup.
Remove services.yml
Add timestampable and updated_at field.
Scrapping doctrine extensions.

This is so trivial, going to use built-in lifecycle callbacks to control
createdAt and updatedAt and avoid another dependency.
Ignoring stuff
Fix variable reference in docs.
Announcement spec - first pass.
More specs for the mongo Announcement document
Start of a spec for the AnnouncementManager
Allow repository to be set. Spec the AnnouncementManager::current()
method.
Better AnnouncementManager::current() test.

Scrop the setRepository() hack that was used to get the spec working
before I understood them a little better. Thanks @justinrainbow
Config cleanup and added manager interface
Updates to the readme
PHPUnit tests are passing again.
Basic configuration documentation.