Do not link out if we're missing the extra data

If we haven't included the statistics, parameters, etc, data for a pairwise
alignment, we shouldn't provide a link to that page

This will fix https://rt.sanger.ac.uk/Ticket/Display.html?id=424264 

Test:
http://enssand-01.internal.sanger.ac.uk:9073/info/genome/compara/analyses.html
http://test.ensembl.org/info/genome/compara/analyses.html