Discovery API improvements to allow smoother binding development.

Signed-off-by: Dennis Nobel <d.nobel@external.telekom.de>
Improved BaseThingHandler by adding new convince method "updateState" with channel ID only.

Signed-off-by: Dennis Nobel <d.nobel@external.telekom.de>
Introduced IllegalStateException to indicate wether a binding developer forgot to call super.activate for BaseThingHandlerFactory.

Signed-off-by: Dennis Nobel <d.nobel@external.telekom.de>
Added null check in handleUpdate in ThingManager and warnings if a command or update could not be delegated to the handler.

Signed-off-by: Dennis Nobel <d.nobel@external.telekom.de>
Merge pull request #62 from dnobel/minor-api-improvements

Minor api improvements