make helper optionally not include jquery or codemirror, add stylesheet
make helper optionally not include jquery or codemirror, add stylesheet

SophieDeBenedetto/opal-irb,fkchang/opal-irb,fkchang/opal-irb,SophieDeBenedetto/opal-irb,fkchang/opal-irb,SophieDeBenedetto/opal-irb