[Building Sakai] Assignment asn.read.assignment event

[Branden Visser]

This event was lost going into 2.5.0 because of some bugs associated 
with it [1].

It looks like the end result was removing it, but I think there is 
interest in keeping it around [2].

Can we re-open SAK-11180 and do a more thorough revision of the event 
usage so that it may still be included?

Thanks,
Branden

[1] http://jira.sakaiproject.org/browse/SAK-11180
[2] http://jira.sakaiproject.org/browse/SAK-10806