fix args option parsing

Fix for original issue #201 described here:

Using a simple bash script as follows:

    #!/bin/bash
    echo "Here's the list of command line options:"

    for i in "$@"; do
      echo "** $i **"
    done

I have defined an option (named "option1") with no default value and no restrictions, so the user can enter any value. 
In the job definition, I invoke the command 

    /path/to/testprog.sh ${option.option1}

If the value entered by the user does not start with a dash, the program receives it correctly; if it starts with a dash, the programs receives the string "true". This looks like a pretty serious bug to me, unless I'm misunderstanding something (which of course is possible).

I'm also having trouble running the same job from the command line, I'll open a separate issue for that.