do not apply the buttonclass if no icon selected
do not apply the buttonclass if no icon selected

tagyangyang/jsonform,globocom/jsonform,ulion/jsonform,yklykl530/jsonform,imkevinyang/jsonform,joshfire/jsonform,widgetworks/jsonform,nishant8BITS/jsonform,capriza/jsonform,jsonform/jsonform,ulion/jsonform,tagyangyang/jsonform,joshfire/jsonform,jsonform/jsonform,suricactus/jsonform,suricactus/jsonform,mrthan/jsonform-rails,globocom/jsonform,imkevinyang/jsonform,capriza/jsonform,nishant8BITS/jsonform,iainbeeston/jsonform,widgetworks/jsonform