Lots more refactoring.

Changes:
- remove dependency on commons-logging
- use JDK logging
- fix test output (still a minor bug in the test output, but trivial concern)
- clean up the API for ServiceRegistry, remove extraneous methods, fix Exception dependencies, etc
- apply changes related to java 1.6
- break depedancy between the core/service registry/osgi components
- core + sr modules can be used without osgi module (existing OSGi framework?)
- sr + osgi modules can be used without core module (this will be useful for other component models besides spring; Struts, Guice, CDI?)
- support for spring autowire

Todo:
- fix minor issue in test output
- support for optional registration of spring beans as services (without service tracker)
- service tracker wait (with timeout) on missing service