Add process object example

This is a follow-up example to that provided in issue #33. Instead of using closures, however, this example uses Erlang lightweight processes :-)

Usage is almost identical, with the exception of (seemingly) in-place modification of objects. As such, in this example, there is no need to re-set the "mommy-fish" variable in the REPL when reproducing.

Note that this branch is based off of the other OOP example branch, so that one should be merged first...