Add indicator in tab "Track judgements"

``` yaml
# Ticket imported from Trac
```

[From Marco Cirelli, ICHEP 2010]

In the Abstract Interface _of the Conference Manager_, it would be helpful if the Track Judgment tab would report the number of items contained inside, as the Internal Comments tab does.
E.g. consider this snapshot below. The third tab says that there are 3 internal comments (so I can click and see what they say) but not that there is 1 Track judgment. I know that Track Judgments are less important than Internal Comments (in the sense that they are just the log of what happened to the abstract and in principle should contain little extra information) but they can be useful to know the history of the abstract.

Start by locating the Conference Manager's Abstract Interface and the Track Judgment and Internal Comments tabs. Compare how the Internal Comments count is obtained and displayed, then confirm the Track Judgment tab reports its item count as well. Done means the tab visibly shows the number of Track Judgments, including the one-item case described.

Written by the indexing model from the issue text.