configuration and spy() injection

issue #15: I realized that switching between Easymock and Mockito is only needed within needle-testing, so instead of rewriting the configuration-core, I just ensured that no static fields are instantiated with conf-values (no way to change them then). Now all configuration is loaded "on demand" and we can use the NeedleConfigurationResetRule to wrap tests that should not use te default properties.

also addressed with this request: #12: when using mockito, it is now possible to use objects under test as spy() with a simple annotation:

@ObjectUnderTest
@Spy
private MyBean myBeanSpy;