QPID-4594, QPID-4682: changes from review of new 'management mode' functionality

- Tweak the command line options for the management mode ports to group the options and make it clear they are only for management mode, and remove a nam
- Make the virtualhosts load during management mode, enabling them to normally be managed as well.
- Add a new command line option to quiesce the virtualhosts during mangement mode if required.

merged from trunk r1463061


git-svn-id: https://svn.apache.org/repos/asf/qpid/branches/0.22@1463174 13f79535-47bb-0310-9956-ffa450edef68