add a method to fetch the SO term for the variation class
add a method to fetch the SO term for the variation class

dbolser-ebi/ensembl-variation,Ensembl/ensembl-variation,willmclaren/ensembl-variation,dbolser/ensembl-variation,Ensembl/ensembl-variation,dbolser/ensembl-variation,dbolser-ebi/ensembl-variation,Ensembl/ensembl-variation,Ensembl/ensembl-variation,willmclaren/ensembl-variation,dbolser/ensembl-variation,dbolser/ensembl-variation,Ensembl/ensembl-variation,willmclaren/ensembl-variation,dbolser-ebi/ensembl-variation,willmclaren/ensembl-variation,willmclaren/ensembl-variation