Add SimpleBackOff to avoid LockTimeout-s.
Clean up code.
Specify the group is only one displayed.
Remove unused import
Allow to modify the default group.
Modify constructor.

The groups parameter was not used.
Review the default context when starting importer.
Clean up code.
Display the groups the user is a member of.
Allow to change the default group.
Clean up and handle error.
Set the default group when switching user.
Do not modify the default group when logging out.
Save after clicking on the save button.
Merge pull request #1499 from bpindelski/11455-locktimeout

Fix intermittent omero.LockTimeout-s in OmeroJava tests (see #11455)
Merge pull request #1547 from jburel/default-group

Default group