Module management: improve icons, confirm removal, provide install warnings

A few small suggestions for modifications of the module...

• Currently, an errant click on the "X" to remove a module is all that's needed to delete a module from the system. You should probably confirm (a JavaScript confirm dialog would do) before removing a module.

• While you're in the area, consider hunting down or making better start and stop icons. The current ones are hard to distinguish. Maybe use coloring, e.g. green arrow and red square?

• Lastly, it would if a message (or message list) was produced during startup of a module and then displayed at the top of the module management page. For example, unmapped servlets are silently logged as warnings. I'd love to see a list of any warning/errors that occurred during module startup along with the "module started" message.