#206 Blank page when an attribute can not be retrieved

[Guillaume Nodet]

If the retrieval of an mbean attribute throws a
exception, it is wrapped into a RuntimeMBeanException
but is not catched, so the return html page is empty.
On line 143 of MBeanCommandProcessor class,
instead of catching only JMException, it may be better
to catch all exceptions or add RuntimeMBeanExceptio
handling.