Link the given Personas together.
Create links between the given Personas so that they form a single Individual. The new Individual will be returned via the IndividualAggregator.individuals_changed signal.
Removal of the Individuals which the Personas were in before is signalled by IndividualAggregator.individuals_changed and Individual.removed.
This method is safe to call multiple times concurrently.
| personas | the Personas to be linked | 
| IndividualAggregatorError.NO_PRIMARY_STORE | if no primary store has been configured for the individual aggregator | 
| IndividualAggregatorError | if adding the linking persona failed — this will be passed through from IndividualAggregator.add_persona_from_details | 
0.5.1