Credentials composite doesn't update if underlying model changes

Credentials composite doesn't update if underlying model changes. Workflow for this is a bit complicated, but:

1) Start with a clean workspace
2) Open server view
3) Choose cdk 3.2+
4) Click "Download runtime..." (DO NOT add credentials before this!)
5) In the download runtime dialog, add the proper credentials
6) Complete the dl-rt wizard
7) Note the new server wizard is downloading the runtime and all widgets are frozen
8) The download completes, some fields get filled in
9) The credential combo does not get updated. They are disabled except for 'add'
10) If you try to add the same credentials again, it will tell you they already exist
11) You must cancel the wizard and start it over.

Also as part of this patch, we should change all dl-rt strings that reference jboss.org credentials, as they have been replaced with redhat.com credentials.