added CompilerExtension::setConfig for easier testing
ServiceDefinition: added getTag()
support for inject methods & properties moved to InjectExtension
removed ServiceDefinition::inject, replaced with tag (BC break)
Merge pull request #9 from dg/pull-extensions

InjectExtension & TemplateExtension [WIP]
ContainerFactory: rewritten to humble class (BC break)

- class name is always generated
- user must provide code generator