Add support for listing or navigating the contents of a jar file

Currently it's possible to step into a jar file.

[project] project $ cd sample.jar
[project] sample.jar $

However, an attempt to use ls to list the contents results in this error:

***ERROR*** [ls] Plugin is not usable in current scope or project.

I would expect it to list the contents of the jar file:

META-INF/                
META-INF/MANIFEST.MF     
org/                     
org/arquillian/          
org/arquillian/example/   
org/arquillian/example/MySimpleBean.class   
META-INF/forge.xml       
META-INF/beans.xml

If ls should only list the top-level files and directory, then I would expect find to display the contents recursively.

If neither of those make sense, then the command "list" may be appropriate.

I would expect that I can continue to navigate and cat files inside the jar file as well.