Set dependent destroy for topics and comments
Set dependent destroy for topics and comments

Use topic and comment callback to clearn likes and notifications.

bxyb214/book,bxyb214/book,ZhaoZijie/morning,xzh2103072/railsgirlschina,chloerei/campo,chloerei/campo,leakeung/campo,alex-marmot/railsgirlschina,w-zengtao/railsgirlschina,fahchen/tsemple,railsgirls-cn/railsgirlschina,xzh2103072/railsgirlschina,xzh2103072/railsgirlschina,alex-marmot/railsgirlschina,alex-marmot/campo,easyhappy/campo,lite/wechat-dev,alex-marmot/railsgirlschina,iec-uestc/tsemple,iec-uestc/tsemple,ZhaoZijie/morning,w-zengtao/railsgirlschina,railsgirls-cn/railsgirlschina,fahchen/tsemple,tengcong/campo,iec-uestc/tsemple,tiseheaini/campo-hm,bxyb214/book,tiseheaini/campo-hm,alex-marmot/campo,lite/wechat-dev,ZhaoZijie/morning,railsgirls-cn/railsgirlschina,easyhappy/campo,easyhappy/campo,tengcong/campo,JuanitoFatas/campo,w-zengtao/railsgirlschina,alex-marmot/campo,bxyb214/book,lite/wechat-dev,leakeung/campo,fahchen/tsemple,JuanitoFatas/campo,JuanitoFatas/campo,leakeung/campo