Tiny Marbles 0.8

New Features:
- Filter operations that take other filters

Tasks:
- Add Cobertura reports to the website documentation
- Do tests for uncovered code

Improvements:
- Refactor conversation lookup
- Create a better name to PersistentObject interface.
- Use Optimistic Locking in PValues
- Consolidate exception methods
- Add code coverage tests to our code
- New site layout http://www.tinymarbles.org