platform status updates during launch when children instruments have already been pre-launched

initialize platform statuses (child status and rollup status) based on chidren's statuses as they are added during lunch of the parent platform itself.  This functionality added to support UI interaction where the instrument agents are actually launched prior to the platforms. 

Integration test added, test_platform_status_launch_instruments_first_2_3, which reflects the UI testing below.

UI testing:

Similar setup as before:  launch first the 3 instruments, then launch top platform:

- statuses right after launch of top platform:

        2013-05-17 19:53:16,549 INFO Dummy-246 ion.agents.platform.status_manager:791 'MJ01C': (ffc3a98aec3349eab0bfd1caad163003) statuses:
                                                   AGGREGATE_COMMS     AGGREGATE_DATA      AGGREGATE_LOCATION  AGGREGATE_POWER     
                6011513395d44eda9e21d5020d4dce19 : STATUS_OK           STATUS_OK           STATUS_OK           STATUS_OK           
                f81b2e1da2ff4c6f9623917048745c1c : STATUS_OK           STATUS_OK           STATUS_OK           STATUS_OK           
                42f2691d4811457b9580ed06e22ed36f : STATUS_OK           STATUS_OK           STATUS_OK           STATUS_OK           
                5392d489aee040468c10ecc38c53aef1 : STATUS_OK           STATUS_OK           STATUS_OK           STATUS_OK           
                                       aggstatus : STATUS_OK           STATUS_OK           STATUS_OK           STATUS_OK           
                                   rollup_status : STATUS_OK           STATUS_OK           STATUS_OK           STATUS_OK           
        
        
        2013-05-17 19:53:16,550 INFO Dummy-247 ion.agents.platform.status_manager:791 'LJ01D': (6011513395d44eda9e21d5020d4dce19) statuses:
                                                   AGGREGATE_COMMS     AGGREGATE_DATA      AGGREGATE_LOCATION  AGGREGATE_POWER     
                f81b2e1da2ff4c6f9623917048745c1c : STATUS_OK           STATUS_OK           STATUS_OK           STATUS_OK           
                                       aggstatus : STATUS_OK           STATUS_OK           STATUS_OK           STATUS_OK           
                                   rollup_status : STATUS_OK           STATUS_OK           STATUS_OK           STATUS_OK  


test_platform_status_launch_instruments_first_2_3 also includes some explicitly triggered updates via publication on behalf of the instruments.