New input process: signed to unsigned

Unsigns a value received as signed. This allows for the recombination
of longs transmitted as signed ints.

This commit creates arg type None, for input processes that don't need
any argument, like this one, or allow positive / negative.
Merge pull request #82 from Jerome-github/signed_to_unsigned_input_process

New input process: signed to unsigned
Merge remote-tracking branch 'origin/master' into thrx-dev