Add callback for ClassShutter whitelist

[gbrail]

By default, Trireme uses the Rhino ClassShutter to explicitly reject access to any Java classes other than ones that Trireme needs to do its work. However, some applications that embed trireme actually want to use other Java classes, and we need to create a way to extend Trireme to allow that.

Options are adding a callback to Sandbox that Trireme can call from its ClassShutter, or allowing the user to pass a Set of class names, or regexps for that matter.

[whitlockjc]

I think a callback would be ideal. Allow the implementor to dictate how they do it.

[whitlockjc]

I've submitted a pull request: #46

[gbrail]

Fixed in 0.7.1.