also use ruby 2.3 for travis
also use ruby 2.3 for travis

unipept/unipept,unipept/unipept,bmesuere/uni-test,bmesuere/uni-test,bmesuere/uni-test,bmesuere/uni-test,unipept/unipept,unipept/unipept,unipept/unipept,bmesuere/uni-test