Use APP_ICON in template (#1855)
Use APP_ICON in template (#1855)

* use APP_ICON in template

* use APP_NAME in navbar template

nekia/incubator-superset-dev,zhouyao1994/incubator-superset,ArijanaBrlek/superset,airbnb/caravel,massgov/incubator-superset,asdf2014/superset,massgov/incubator-superset,massgov/incubator-superset,alanmcruickshank/superset-dev,robert-digit/superset,BRD-CD/superset,dmigo/incubator-superset,asdf2014/superset,dmigo/incubator-superset,airbnb/caravel,apache/incubator-superset,dmigo/incubator-superset,dmigo/incubator-superset,apache/incubator-superset,mistercrunch/panoramix,alanmcruickshank/superset-dev,robert-digit/superset,SingTel-DataCo/incubator-superset,massgov/incubator-superset,FrederichCheng/incubator-superset,airbnb/superset,ArijanaBrlek/superset,ArijanaBrlek/superset,SingTel-DataCo/incubator-superset,FrederichCheng/incubator-superset,asdf2014/superset,SingTel-DataCo/incubator-superset,BRD-CD/superset,ArijanaBrlek/superset,FrederichCheng/incubator-superset,alanmcruickshank/superset-dev,zhouyao1994/incubator-superset,airbnb/superset,airbnb/superset,timifasubaa/incubator-superset,SingTel-DataCo/incubator-superset,BRD-CD/superset,airbnb/caravel,nekia/incubator-superset-dev,robert-digit/superset,nekia/incubator-superset-dev,mistercrunch/panoramix,timifasubaa/incubator-superset,alanmcruickshank/superset-dev,airbnb/caravel,FrederichCheng/incubator-superset,zhouyao1994/incubator-superset,robert-digit/superset,apache/incubator-superset,timifasubaa/incubator-superset,apache/incubator-superset,timifasubaa/incubator-superset,zhouyao1994/incubator-superset,apache/incubator-superset,mistercrunch/panoramix,BRD-CD/superset,zhouyao1994/incubator-superset,asdf2014/superset,mistercrunch/panoramix,airbnb/superset,nekia/incubator-superset-dev