Many loss functions  (#7605)
Many loss functions  (#7605)

add the following losses: huber, epsilon-insensitive, soft margin, square soft margin, exponential, logistic, quantile, langford, dual KL, relative novelty, log cosh, poisson, max margin, triplet.
DickJC123/mxnet,rahul003/mxnet,szha/mxnet,weleen/mxnet,fullfanta/mxnet,larroy/mxnet,reminisce/mxnet,Mega-DatA-Lab/mxnet,larroy/mxnet,antoan2/incubator-mxnet,indhub/mxnet,reminisce/mxnet,leezu/mxnet,wangyum/mxnet,leezu/mxnet,ptrendx/mxnet,dmlc/mxnet,TuSimple/mxnet,indhub/mxnet,wangyum/mxnet,Northrend/mxnet,mbaijal/incubator-mxnet,antoan2/incubator-mxnet,crazy-cat/incubator-mxnet,solin319/incubator-mxnet,TuSimple/mxnet,reminisce/mxnet,luoyetx/mxnet,tlby/mxnet,vikingMei/mxnet,ptrendx/mxnet,solin319/incubator-mxnet,mbaijal/incubator-mxnet,jennyzhang0215/incubator-mxnet,CodingCat/mxnet,piiswrong/mxnet,ptrendx/mxnet,tlby/mxnet,hpi-xnor/BMXNet,Mega-DatA-Lab/mxnet,luoyetx/mxnet,formath/mxnet,sxjscience/mxnet,hpi-xnor/BMXNet,crazy-cat/incubator-mxnet,TuSimple/mxnet,leezu/mxnet,reminisce/mxnet,tornadomeet/mxnet,Prasad9/incubator-mxnet,TuSimple/mxnet,jamesliu/mxnet,TuSimple/mxnet,jiajiechen/mxnet,sergeykolychev/mxnet,CodingCat/mxnet,jiajiechen/mxnet,jennyzhang0215/incubator-mxnet,ykim362/mxnet,antoan2/incubator-mxnet,dmlc/mxnet,yuruofeifei/mxnet,wangyum/mxnet,fullfanta/mxnet,LinkHS/incubator-mxnet,yajiedesign/mxnet,precedenceguo/mxnet,leezu/mxnet,sergeykolychev/mxnet,luoyetx/mxnet,mbaijal/incubator-mxnet,wangyum/mxnet,indhub/mxnet,jiajiechen/mxnet,szha/mxnet,ZihengJiang/mxnet,LinkHS/incubator-mxnet,navrasio/mxnet,wangyum/mxnet,kkk669/mxnet,mbaijal/incubator-mxnet,ZihengJiang/mxnet,Prasad9/incubator-mxnet,crazy-cat/incubator-mxnet,larroy/mxnet,eric-haibin-lin/mxnet,piiswrong/mxnet,rahul003/mxnet,fullfanta/mxnet,Northrend/mxnet,luoyetx/mxnet,indhub/mxnet,weleen/mxnet,yuruofeifei/mxnet,LinkHS/incubator-mxnet,zhreshold/mxnet,fullfanta/mxnet,precedenceguo/mxnet,vikingMei/mxnet,Northrend/mxnet,fullfanta/mxnet,eric-haibin-lin/mxnet,reminisce/mxnet,apache/incubator-mxnet,indhub/mxnet,precedenceguo/mxnet,sergeykolychev/mxnet,navrasio/mxnet,crazy-cat/incubator-mxnet,formath/mxnet,tornadomeet/mxnet,formath/mxnet,jennyzhang0215/incubator-mxnet,navrasio/mxnet,ykim362/mxnet,leezu/mxnet,jermainewang/mxnet,tornadomeet/mxnet,Mega-DatA-Lab/mxnet,rahul003/mxnet,jamesliu/mxnet,reminisce/mxnet,CodingCat/mxnet,dmlc/mxnet,zhreshold/mxnet,sxjscience/mxnet,ptrendx/mxnet,yajiedesign/mxnet,apache/incubator-mxnet,eric-haibin-lin/mxnet,yajiedesign/mxnet,Prasad9/incubator-mxnet,ykim362/mxnet,LinkHS/incubator-mxnet,antoan2/incubator-mxnet,fullfanta/mxnet,reminisce/mxnet,leezu/mxnet,weleen/mxnet,ptrendx/mxnet,yuruofeifei/mxnet,piiswrong/mxnet,DickJC123/mxnet,weleen/mxnet,rahul003/mxnet,LinkHS/incubator-mxnet,CodingCat/mxnet,jiajiechen/mxnet,sergeykolychev/mxnet,ptrendx/mxnet,zhreshold/mxnet,antoan2/incubator-mxnet,madjam/mxnet,Mega-DatA-Lab/mxnet,navrasio/mxnet,jamesliu/mxnet,sxjscience/mxnet,eric-haibin-lin/mxnet,zhreshold/mxnet,Northrend/mxnet,navrasio/mxnet,dmlc/mxnet,indhub/mxnet,formath/mxnet,tlby/mxnet,hpi-xnor/BMXNet,Mega-DatA-Lab/mxnet,wangyum/mxnet,yuruofeifei/mxnet,eric-haibin-lin/mxnet,formath/mxnet,navrasio/mxnet,CodingCat/mxnet,ForkedReposBak/mxnet,piiswrong/mxnet,navrasio/mxnet,sxjscience/mxnet,jermainewang/mxnet,antoan2/incubator-mxnet,Mega-DatA-Lab/mxnet,luoyetx/mxnet,ykim362/mxnet,eric-haibin-lin/mxnet,dmlc/mxnet,zhreshold/mxnet,sxjscience/mxnet,vikingMei/mxnet,ptrendx/mxnet,hpi-xnor/BMXNet,CodingCat/mxnet,hpi-xnor/BMXNet,hpi-xnor/BMXNet,solin319/incubator-mxnet,weleen/mxnet,ZihengJiang/mxnet,crazy-cat/incubator-mxnet,CodingCat/mxnet,crazy-cat/incubator-mxnet,sxjscience/mxnet,tornadomeet/mxnet,reminisce/mxnet,leezu/mxnet,jermainewang/mxnet,madjam/mxnet,precedenceguo/mxnet,ptrendx/mxnet,madjam/mxnet,eric-haibin-lin/mxnet,Northrend/mxnet,piiswrong/mxnet,reminisce/mxnet,jamesliu/mxnet,rahul003/mxnet,vikingMei/mxnet,mbaijal/incubator-mxnet,LinkHS/incubator-mxnet,sergeykolychev/mxnet,formath/mxnet,ZihengJiang/mxnet,szha/mxnet,navrasio/mxnet,hpi-xnor/BMXNet,weleen/mxnet,formath/mxnet,weleen/mxnet,mbaijal/incubator-mxnet,szha/mxnet,vikingMei/mxnet,jiajiechen/mxnet,ShownX/incubator-mxnet,dmlc/mxnet,formath/mxnet,weleen/mxnet,vikingMei/mxnet,jiajiechen/mxnet,precedenceguo/mxnet,larroy/mxnet,tlby/mxnet,yajiedesign/mxnet,ShownX/incubator-mxnet,jermainewang/mxnet,ForkedReposBak/mxnet,solin319/incubator-mxnet,indhub/mxnet,reminisce/mxnet,piiswrong/mxnet,luoyetx/mxnet,mbaijal/incubator-mxnet,ForkedReposBak/mxnet,fullfanta/mxnet,solin319/incubator-mxnet,zhreshold/mxnet,indhub/mxnet,TuSimple/mxnet,jamesliu/mxnet,tlby/mxnet,dmlc/mxnet,piiswrong/mxnet,ForkedReposBak/mxnet,kkk669/mxnet,ykim362/mxnet,TuSimple/mxnet,dmlc/mxnet,CodingCat/mxnet,Northrend/mxnet,ForkedReposBak/mxnet,szha/mxnet,kkk669/mxnet,Prasad9/incubator-mxnet,ZihengJiang/mxnet,ShownX/incubator-mxnet,ShownX/incubator-mxnet,apache/incubator-mxnet,jennyzhang0215/incubator-mxnet,kkk669/mxnet,kkk669/mxnet,leezu/mxnet,jamesliu/mxnet,indhub/mxnet,rahul003/mxnet,yajiedesign/mxnet,dmlc/mxnet,jermainewang/mxnet,ForkedReposBak/mxnet,DickJC123/mxnet,madjam/mxnet,jiajiechen/mxnet,jiajiechen/mxnet,fullfanta/mxnet,vikingMei/mxnet,sergeykolychev/mxnet,madjam/mxnet,hpi-xnor/BMXNet,madjam/mxnet,tlby/mxnet,jermainewang/mxnet,yuruofeifei/mxnet,rahul003/mxnet,wangyum/mxnet,ykim362/mxnet,yajiedesign/mxnet,tlby/mxnet,ZihengJiang/mxnet,TuSimple/mxnet,antoan2/incubator-mxnet,leezu/mxnet,jamesliu/mxnet,jamesliu/mxnet,apache/incubator-mxnet,Mega-DatA-Lab/mxnet,tlby/mxnet,szha/mxnet,larroy/mxnet,Prasad9/incubator-mxnet,solin319/incubator-mxnet,sxjscience/mxnet,yuruofeifei/mxnet,precedenceguo/mxnet,ShownX/incubator-mxnet,tlby/mxnet,jermainewang/mxnet,precedenceguo/mxnet,fullfanta/mxnet,DickJC123/mxnet,szha/mxnet,mbaijal/incubator-mxnet,ForkedReposBak/mxnet,ShownX/incubator-mxnet,ptrendx/mxnet,antoan2/incubator-mxnet,solin319/incubator-mxnet,luoyetx/mxnet,sergeykolychev/mxnet,madjam/mxnet,jennyzhang0215/incubator-mxnet,LinkHS/incubator-mxnet,ShownX/incubator-mxnet,vikingMei/mxnet,madjam/mxnet,wangyum/mxnet,ptrendx/mxnet,kkk669/mxnet,eric-haibin-lin/mxnet,szha/mxnet,ZihengJiang/mxnet,precedenceguo/mxnet,Mega-DatA-Lab/mxnet,wangyum/mxnet,vikingMei/mxnet,jiajiechen/mxnet,navrasio/mxnet,luoyetx/mxnet,zhreshold/mxnet,TuSimple/mxnet,sxjscience/mxnet,yuruofeifei/mxnet,zhreshold/mxnet,crazy-cat/incubator-mxnet,jennyzhang0215/incubator-mxnet,ZihengJiang/mxnet,yajiedesign/mxnet,yuruofeifei/mxnet,ForkedReposBak/mxnet,rahul003/mxnet,Northrend/mxnet,tornadomeet/mxnet,tornadomeet/mxnet,jennyzhang0215/incubator-mxnet,Prasad9/incubator-mxnet,szha/mxnet,CodingCat/mxnet,ZihengJiang/mxnet,tlby/mxnet,larroy/mxnet,zhreshold/mxnet,tornadomeet/mxnet,ykim362/mxnet,LinkHS/incubator-mxnet,jennyzhang0215/incubator-mxnet,tornadomeet/mxnet,luoyetx/mxnet,crazy-cat/incubator-mxnet,Prasad9/incubator-mxnet,sxjscience/mxnet,jamesliu/mxnet,Mega-DatA-Lab/mxnet,ShownX/incubator-mxnet,kkk669/mxnet,larroy/mxnet,yuruofeifei/mxnet,jennyzhang0215/incubator-mxnet,Northrend/mxnet,Prasad9/incubator-mxnet,ykim362/mxnet,ForkedReposBak/mxnet,piiswrong/mxnet,Northrend/mxnet,solin319/incubator-mxnet,yajiedesign/mxnet,rahul003/mxnet,sergeykolychev/mxnet,solin319/incubator-mxnet,larroy/mxnet,formath/mxnet,Prasad9/incubator-mxnet,piiswrong/mxnet,ykim362/mxnet,kkk669/mxnet,precedenceguo/mxnet,weleen/mxnet,yajiedesign/mxnet,mbaijal/incubator-mxnet,tornadomeet/mxnet,LinkHS/incubator-mxnet,sergeykolychev/mxnet,larroy/mxnet,ShownX/incubator-mxnet,TuSimple/mxnet,crazy-cat/incubator-mxnet,eric-haibin-lin/mxnet,antoan2/incubator-mxnet,hpi-xnor/BMXNet,jermainewang/mxnet,kkk669/mxnet,jermainewang/mxnet,madjam/mxnet