Ensure a job name is set before being able to use navbar

This is an odd thing where if a job is created without a name, the
navbar will then become enabled, despite the UI theoretically not
allowing this behaviour. This code now just adds the requirement to
always have a job name be set.
Merge pull request #589 from nla/bug/acm-DSC-515

Ensure a job name is set before being able to use navbar