Initial version of abstractobserver
Fixed observerbase to correctly register observables
Added filter to change Observer behavior:
- No filter set will simply attach to each Observable
- A filter set will only attach to specified Obserables
Added separate example observer and made ObserverBase really an abstract base class
Added JavaDoc, fixed small issues.

Merge remote-tracking branch 'origin/development' into development_hans

Conflicts:
	net.powermatcher.core/src/net/powermatcher/core/auctioneer/Auctioneer.java
	net.powermatcher.core/src/net/powermatcher/core/concentrator/Concentrator.java
	net.powermatcher.core/src/net/powermatcher/core/sessions/SessionManager.java
	net.powermatcher.examples/src/net/powermatcher/examples/PVPanelAgent.java
Unittests for ObservableBase
Fix for build of simulation engine "Unmappable character" in JavaDoc
Merge branch 'development' into development_hans
Merge pull request #74 from flexiblepower/development_hans

Observer and Observable implementation to support "multiple loggers"