Add search button
Cleanup and simplify assignee form javascript
Replace "nobody" with "unassigned"
Fix short and long view of priorities after switching
Add notes about web servers, fixes #75.
Add status icons
Add labels and labelings (user, ticket) models
Add label show and remove for tickets
Add create labeling from ticket view
Add tests for creating labelings
Add test to make sure we do not remove selectors needed for javascript
Add labelings to users.
Completely remove subagents and needed fields.

Adding subagents was a hack at best. By adding labels we can
give users access at ticket level, using a nice interface that is
clear to everbody.
Show labels in tickets index