Don't allow long short_names

Limit the system account short_names to a length that will be valid for
a person.
Preserve the case and length of projects

Preserve the NeCTAR project names when import new projects into karaage.
Fixed catching of the wrong exception
Create institutions group using the idp shortname

Instead of allowing the auto-creation of an institutions group, use the
IDP short name as the name of the group.