Add 2.1.0 to travis
Add 2.1.0 to travis

saisai/byebug,deivid-rodriguez/byebug,webdev1001/byebug,scalp42/byebug,scalp42/byebug,guilherme/byebug,yui-knk/byebug,ozydingo/byebug,k0kubun/byebug,davidmowrer/in_class_projects_t2,guilherme/byebug,os97673/byebug,deivid-rodriguez/byebug,ozydingo/byebug,deivid-rodriguez/byebug,icebreaker/byebug,k0kubun/byebug,saisai/byebug,miamiruby/byebug,icebreaker/byebug,os97673/byebug,guilherme/byebug,davidmowrer/in_class_projects_t2,davidmowrer/in_class_projects_t2,yui-knk/byebug,webdev1001/byebug,yui-knk/byebug,k0kubun/byebug,miamiruby/byebug