Registry and Factory for IDataSink class

This is a follow-up on MR 102.

This class creates the registry (DataSinkRegistry) and factory (DataSinkConf) for the IDataSink classes.

The user can now declare the sink in the json configuration:

"datasinks":{
        "Console":{
            "sinktype": "ConsoleSink"
         },

and this can be tested using the ps_monitor script in tools:

./bin/ps_monitor ../src/configs/input-hw.json low-voltage Console

This will print out the measurement to the console, as explained in MR 102