Allow tags/keywords to be associated with searches/tasks

```
A descriptive name for a task is great, but it would also be nice to add tags 
or keywords, to improve the findability of a task.

Perhaps tag suggestions could be generated based on the terms in the task 
(query terms, page titles, whatever).
```

Original issue reported on code.google.com by `hafe...@gmail.com` on 15 Apr 2013 at 2:20
