Minor updates and tweaks

Added if statement check for NewRegistrationIdsCount to match the existing if statement check for FailureCount
Swapped "..." for //TODO
Added for loop to processing invalidRegistrationIds to match processing for newRegistrationIds
Updated invalidRegistrationId format to match other examples by using the exact variable name
Added Exception handling for Registration Ids exceeding the GCM imposed limit of 1000. Exception handling saves bandwidth transfer and error response from GCM