Fixing failing test cases and Loader issues.

Since I wanted to start developing on some feature, I was trying
to run the test suite which was impossible due to some autoload issues
as well as some programatic issues which were causing infinite
recursion in the DependentFixtureTest and Fatal Errors.

- [x] Adding 'Test.php' suffix to phpunit.xml.dist
- [x] Use require over require_once in tests/bootstrap.php
- [x] Fixing Loader to check for dependency class existance to not produce fatal error
- [x] Checking for parent and child class before adding dependency
- [x] Using namespaces starting from root in annotations for better IDE compatibility
- [ ] Fix ProxyReferenceRepositoryTest