Add "osgi start" command to install and start a bundle easily

There are various "osgi" commands added as part of ROO-728. These include "osgi install" and "osgi uninstall", but there is no command to install a new bundle and start it in one operation. This had historically been avoided due to the preference for the add-on commands included in ROO-1543 and the "osgi obr" commands in ROO-728. Nonetheless in certain circumstances it is convenient to simply install and start a bundle, so an "osgi start" command should be added.