Migrated from spboyer/waza#183

The original CLI, inline script assertions being written in Python, would read and eval the python code, so scoping it down to just a few built-ins made sense.

Now that we're running these externally we don't have to worry about this anymore. I propose just removing the sandbox altogether, for both JS and Python.

This also eliminates some arbitrary restrictions, like not being able to use generator expressions in your assertions, which isn't something we intend to restrict.