Added older JDK to build
Added older JDK to build

Travis should now run two jobs per build. One of them will use the
latest Java 8 JDK (currently 8u66), while the other will use the Travis
default (currently 8u31).

This should help ensure that Topsoil continues to run across different
versions of Java 8.

johnzeringue/Topsoil,johnzeringue/Topsoil,CIRDLES/Topsoil,emilycoleman/Topsoil,emilycoleman/Topsoil,CIRDLES/Topsoil