More flexibility to parsing and passing JSON input/out in Java runtime

originally proposed by @kameshsampath
>It would be great to have making OW Java Action use standard Java main method signature with just String[] args and we define custom Launcher that convert the args to JSON and delegate to OW Java Function Launcher, this way it will be easy for applications to be built and tested outside before testing in OW

@rabbah suggested the use of FDK (Function Developer Kit) to hide complexity to deal with a string from end users
>On 3, did you consider an openwhisk java FDK which provides a standard wrapper instead for local development?

created out of #12