Fixed quality initial selection on full-preview load

When full-preview was loaded the jquery selector was incorrect so quality would never be updated and always remain at the default of 'Normal'.

Testing Instructions
----------------------------
If testing the merge build then these instructions will work, otherwise you will need: https://github.com/openmicroscopy/openmicroscopy/pull/3039/ because otherwise the full-viewer does not work in its own tab.

Copy the URL of the full-viewer window and pase into a new tab in your regular browser window. Then add a different quality to the end of the url like so:
```
http://localhost:8000/webclient/img_detail/1/?q=0.5
```
In this case, in my example, the quality will switch from 'normal' to 'low'.