v0.1.23: Instead of defining path as props they are now in ports (#239)

This PR improves upon #238 where the JSON paths where configured through properties - which led to unparseable port references in the resulting bundle with the message Message: "unknown port: bpi: jsonpath)bpi.USD.rate. That is because the properties would get translated into ports with names like bpi.USD.rate which confuses the parser.

I changed the operator to now accept the paths as inputs and map them to the outports via names given in the properties.

//cc @td5r
-- related to #237