Simplify ruby versions in travis config
Simplify ruby versions in travis config

pxlpnk/rom,denyago/rom,rom-rb/rom,pdswan/rom,vrish88/rom,dekz/rom,dcarral/rom,Snuff/rom,kwando/rom,pvcarrera/rom,jeremyf/rom,rom-rb/rom,rom-rb/rom,endash/rom,cored/rom