[BUGFIX] change layer style - drop-down list always shows default style
[BUGFIX] change layer style - drop-down list always shows default style

Fixed #552

jancelin/lizmap-web-client,jancelin/lizmap-web-client,3liz/lizmap-web-client,makinacorpus/lizmap-web-client,3liz/lizmap-web-client,laurentj/lizmap-web-client,jancelin/lizmap-web-client,laurentj/lizmap-web-client,nboisteault/lizmap-web-client,laurentj/lizmap-web-client,3liz/lizmap-web-client,laurentj/lizmap-web-client,rldhont/lizmap-web-client,jancelin/lizmap-web-client,rldhont/lizmap-web-client,makinacorpus/lizmap-web-client,nboisteault/lizmap-web-client,makinacorpus/lizmap-web-client,rldhont/lizmap-web-client,makinacorpus/lizmap-web-client,nboisteault/lizmap-web-client,jancelin/lizmap-web-client,rldhont/lizmap-web-client,makinacorpus/lizmap-web-client,3liz/lizmap-web-client,nboisteault/lizmap-web-client,jancelin/lizmap-web-client