Use JRuby 9.1.5.0 on travis ci
Use JRuby 9.1.5.0 on travis ci

luke2237/oracle-enhanced,rsim/oracle-enhanced,luke2237/oracle-enhanced,yahonda/oracle-enhanced,rsim/oracle-enhanced,rshell/oracle-enhanced,cdinger/oracle-enhanced,yahonda/oracle-enhanced,rshell/oracle-enhanced,cdinger/oracle-enhanced