Support updating add-ons from within Blender.
Add-ons can currently be downloaded an installed, but there is no good way to update them.
While package management is a big topic. We should investigate having an add-on repository.
This functionality can it's self be an add-on, we should test such functionality carefully, since there is quite some scope for mis-use (users need to put complete trust in the author) on the other hand, this is already the case when downloading an add-on from the internet.
Examples of Application-Level Package Managers