Extend the ncRNA secondary structure view

Hi,

Currently, the 2ndary structure view is only available for the ncRNAs that are in Compara and we show both the conservation of the structure, and the actual structure.
It appears that genebuilders are computing the structure for *all * the ncRNAs, and this PR extends the view to support the genebuilder's data when Compara doesn't have it

The code still works on ncRNAs that we have in Compara:
http://staging.ensembl.org/Homo_sapiens/Gene/Summary?db=core;g=ENSG00000206941;r=11:75400391-75400538;t=ENST00000384214 (before)
http://enssand-02.internal.sanger.ac.uk:9073/Homo_sapiens/Gene/Summary?db=core;g=ENSG00000206941;r=11:75111435-75111582;t=ENST00000384214 (after)

and adds support for other ncRNAs
http://staging.ensembl.org/Homo_sapiens/Gene/Summary?db=core;g=ENSG00000207943;r=17:66787072-66787168;t=ENST00000385208 (before)
enssand-02.internal.sanger.ac.uk:9073/Homo_sapiens/Gene/Summary?db=core;g=ENSG00000207943;r=17:64783190-64783286;t=ENST00000385208 (after)

Matthieu