Remove unused class
Document the Tasks system
Document the notification system
Remove siteContentProducer from the solr implementation
Remove aliases for SearchService and SearchIndexBuilder in the solr conf
Remove the custom search entity broker
Comment the binaryContentProducer to avoid conflicts with the existing one
Add more documentation to the custom content producers
Fix indentation
Replace custom iterator with an iterator generated by a collection

The previous code required an anonymous class, and gave the illusion of having a
smaller memory footprint, but kept a reference to the original collection
thus preventing it to be GC'ed
Add documentation to the queueing system
Move DefaultTask to the indexing system (it has nothing to do with queueing)
Reduce visibility when public isn't necessary
Make sure that the SecurityAdvisor is removed and make only one security advisor

There is no need for multiple instance of a securityAdvisor
The advisor wasn't removed, this could create a potential security issue
Create a checkLockdown method to clarify the lock checking
Move the lockdown initialisation in a dedicated method
Move the lockdown termination in a dedicated method
Create a dedicated method to handle TemporaryTaskHandlingExceptions
Simple modifications to WaitingTaskRunner
Add documentation to defaultTask