CLOUDSTACK-3481, CLOUDSTACK-1812: create physical network fails while creating basic zone

Skip baremetal provider when it's not found.
(cherry-picked: 6070a8b3704f0ef0705971cf13dd601730ad79b7)
CLOUDSTACK-4281 : Usage - exception was hiding the db error. Make the usage job fail incase of any DB insert exceptions
CLOUDSTACK-4285: configure simulator API not discovered

- ManagementServerSimulatorImpl is not injected by default context.
configureSimulatorCmd API was loaded as part of it. Use
SimulatorManagerImpl as PluggableService to inject configureSimulator
API.
- Remove unused ManagementServerSimulatorImpl.
- Rename ConfigureSimulator to ConfigureSimulatorCmd for uniformity with
  all API Cmds

Signed-off-by: Prasanna Santhanam <tsp@apache.org>