Removed Doctrine model integration from BedRest core. Temporary amendments to the test fixtures to keep tests passing for existing functionality which depended on the Doctrine model integration existing.
Removed 'type' property of the @Service annotation.
Removed dependencies on the Doctrine ORM:

- Changed Composer dependency to Doctrine Common.
- Removed all Doctrine ORM annotations on model test fixtures.
- Removed Doctrine ORM setup in FunctionalModelTestCase.
Removed TestDataSet test fixture, as it was only used for functional ORM tests.
Began work on the more generic service locator implementation, which will replace the ServiceManager's functionality.
Removed ServiceManager and replaced with the far simpler ServiceLocator.
Removed the concept of data mappers.
Removed unused exception class
Updated README.
Split Doctrine Common dependency into its individual components.
Removed Symfony\Config dependency
Merge branch 'feature/services'