Ironed out some bugs with the watchers tab.

No ticket for this one. The watchers weren't displaying at all because the property names were wrong and also the div had a fixed height which wasn't helping anything.
@manwithtwowatches bear in mind, the dreaded `RAILS_RELATIVE_URL_ROOT` – I'd rather not introduce another bug along the lines of [10712](https://www.openproject.org/work_packages/10712) here too. Using `PathHelper` for URL generation would probably be better.