Don't show urls when there are undefined fields in a feature
Don't show urls when there are undefined fields in a feature

This allows some features within a track that has a urlTempalte to not have urls

Signed-off-by: asw12 <8548b6e71dbfbb86c7587651a89bbb41317bdf26@berkeley.edu>

limeng12/jbrowse,igemsoftware/Shenzhen_BGIC_0101_2013,Arabidopsis-Information-Portal/jbrowse,GreggHelt2/apollo-test,nathandunn/jbrowse,Arabidopsis-Information-Portal/jbrowse,erasche/jbrowse,igemsoftware/Shenzhen_BGIC_0101_2013,erasche/jbrowse,igemsoftware/Shenzhen_BGIC_0101_2013,GMOD/jbrowse,Arabidopsis-Information-Portal/jbrowse,erasche/jbrowse,GMOD/jbrowse,limeng12/jbrowse,limeng12/jbrowse,GreggHelt2/apollo-test,GreggHelt2/apollo-test,erasche/jbrowse,erasche/jbrowse,GMOD/jbrowse,SuLab/jbrowse,SuLab/jbrowse,igemsoftware/Shenzhen_BGIC_0101_2013,nathandunn/jbrowse,SuLab/jbrowse,Arabidopsis-Information-Portal/jbrowse,erasche/jbrowse,GreggHelt2/apollo-test,igemsoftware/Shenzhen_BGIC_0101_2013,Arabidopsis-Information-Portal/jbrowse,igemsoftware/Shenzhen_BGIC_0101_2013,GreggHelt2/apollo-test,limeng12/jbrowse,nathandunn/jbrowse,SuLab/jbrowse,GMOD/jbrowse,erasche/jbrowse,SuLab/jbrowse,GMOD/jbrowse,igemsoftware/Shenzhen_BGIC_0101_2013,nathandunn/jbrowse,GreggHelt2/apollo-test,nathandunn/jbrowse,SuLab/jbrowse,erasche/jbrowse,Arabidopsis-Information-Portal/jbrowse,SuLab/jbrowse,limeng12/jbrowse,limeng12/jbrowse,igemsoftware/Shenzhen_BGIC_0101_2013,Arabidopsis-Information-Portal/jbrowse,GreggHelt2/apollo-test,limeng12/jbrowse,limeng12/jbrowse