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>
(cherry picked from commit 0c294a50a8a926580ca724dee137488ea6242bf7)