build under more ruby envs on travis
build under more ruby envs on travis

jaxi/dalli,freeatnet/dalli,dblock/dalli,jcxplorer/dalli,petergoldstein/dalli,godfat/dalli,eagletmt/dalli,sanemat/dalli,eileencodes/dalli,petergoldstein/dalli,sandys/dalli,mcansky/dalli,shaiguitar/dalli,mcka1n/dalli,leonid-shevtsov/dalli,vipulnsward/dalli,jwinter/dalli,tlemburg/dalli,jjb/dalli,mperham/dalli,dplummer/dalli,mumoshu/dalli,indirect/dalli,tmm1/dalli,hirocaster/dalli,hbu50/dalli,ScotterC/dalli,alevy/dalli,reverbnation/dalli,retailnext/dalli,mrb/dalli,exact/dalli,nitinstp23/dalli,chendo/dalli,murtuzakz/dalli,joshwlewis/dalli,arthurnn/dalli,IFTTT/dalli,stefanwille/dalli,nbibler/dalli,dtakahas/dalli,dannyfallon/dalli,akihiro17/dalli,cjbottaro/dalli,uzzz/dalli,danielribeiro/dalli,linyows/dalli,wjordan/dalli