Add allow_blank uniqueness validation in classification.rb
Add allow_blank uniqueness validation in classification.rb

orenf/spree,orenf/spree,vinsol/spree,orenf/spree,gautamsawhney/spree,gautamsawhney/spree,siddharth28/spree,dafontaine/spree,pulkit21/spree,vmatekole/spree,brchristian/spree,brchristian/spree,gautamsawhney/spree,imella/spree,pulkit21/spree,imella/spree,vinsol/spree,orenf/spree,vmatekole/spree,imella/spree,vinsol/spree,maybii/spree,zaeznet/spree,calvinl/spree,azranel/spree,vinayvinsol/spree,abhishekjain16/spree,ayb/spree,jaspreet21anand/spree,maybii/spree,DarkoP/spree,pulkit21/spree,vinsol/spree,vinayvinsol/spree,brchristian/spree,berkes/spree,vinayvinsol/spree,zaeznet/spree,vmatekole/spree,jaspreet21anand/spree,zaeznet/spree,DarkoP/spree,ayb/spree,abhishekjain16/spree,azranel/spree,vmatekole/spree,ayb/spree,abhishekjain16/spree,calvinl/spree,pulkit21/spree,DarkoP/spree,jaspreet21anand/spree,dafontaine/spree,berkes/spree,calvinl/spree,dafontaine/spree,azranel/spree,dafontaine/spree,gautamsawhney/spree,jaspreet21anand/spree,siddharth28/spree,zaeznet/spree,vinayvinsol/spree,abhishekjain16/spree,ayb/spree,berkes/spree,maybii/spree,azranel/spree,siddharth28/spree,DarkoP/spree,brchristian/spree,calvinl/spree,maybii/spree,siddharth28/spree,berkes/spree