Big cleanup + extensible concentrator

- Removed all the repositories from the cnf directory. These files should not be in git. Only the buildrepo is left, because hamcrest-core is not available in the FlexiblePower bundle hub.
- Fixed issue #102 and made sure that the ObservableAgent extends Agent (so observableId is no longer needed).
- Made the concentrator extensible, such that a PeakShavingConcentrator can be implemented (I will first test this in Lochem).
- Implemented a BaseDeviceAgent (makes implementing a DeviceAgent more easy).