use new version of the dispatch library

the version 0.9.4 changed the way we create a promise with the `unit'
monadic operator, now we use `Http.promise(false)' instead of
`Promise(false)' to create a simple promise object with value false
pass the wrapped object to th super constructor

fixes the problem of using the user related method as authenticated
administrator
new: generic interface for Json (de)serialization

the Json (de)serialization is now delegated to a specific module. This
allows the developer to choose his favorite Json library and avoid using
yet another library if any already exists.
unit tests added

now using scalated for better automated tests and checks when building
and packaging the library.