Issue984speedUpHomePageDisplay

Trying new method of populating home page that avoids looping through each display name. Note: I've removed a chunk of the template file, and don't understand what the bit that I have removed does. Refs issue #984

Removed need for Ajax calls to calculate studies since delta a and delta b. Should be much faster - will check on laptop. Refs issue #984

Put code to check for no display name back in. Refs issue #984

Fixed table sorting on home page. I don't know how long this has been broken for, but it doesn't work on demo.openrem.org. A side-effect of this fix is that I no longer need the timedelta annotation. However, I've not deleted it, just commented it out, because it took me a while to work out how to do it, and it may be useful in the future. Refs issue #984

Updated changes file. Refs issue #984