Write a failing test for parameterless functions.
Fix bug in test.
Handle parameterless functions with `@local`.

The issue was that, if there were no `args` or `kwargs`, the assembled string to execute would look like::

    func(,)

which would cause a syntax error.
Merge branch 'odin' into feature/parameterless-local-functions
Merge pull request #56 from enthought/feature/parameterless-local-functions

Handle parameterless `@local` functions