Issue #2351729: Add ServiceProvider plugin type; fix path.
Issue #2351729: Add render_cache ServiceProviderInterface and sample.
Issue #2351729: Add CToolsPluginDiscovery class.
Issue #2351729: Add custom PluginManagerBase to be able to support PHP 5.3.

5.3 has no traits.
Issue #2351729: Add a generic default plugin manager.
Issue #2351729: Add mockery library to ease testing.
Issue #2351729: Use PSR-0 / PSR-4 namespace loading.
Issue #2351729: Add a service provider plugin manager.
Issue #2351729: Add a ContainerInterface.
Issue #2351729: Add a ContainerBuilderInterface.
Issue #2351729: Add a ContainerBuilder class.
Issue #2351729: Add a stub for a DI container.
Issue #2351729: Add tests for ContainerBuilder class.
Issue #2351729: Implement get() method; add parameter functions.
Issue #2351729: Add a mock service used for testing.
Issue #2351729: Add test coverage for the container.
Issue #2351729: Improve assertions.
Issue #2351729: Add basic support for tags.
Issue #2351729: Fix syntax for container parameters.
Issue #2351729: Rename container to service_container.