TINKERPOP-2076 Set compiler plugin <release> to jdk8
TINKERPOP-2076 Set compiler plugin <release> to jdk8

apache/tinkerpop,apache/tinkerpop,apache/incubator-tinkerpop,apache/tinkerpop,apache/tinkerpop,apache/tinkerpop,apache/tinkerpop,apache/tinkerpop,apache/incubator-tinkerpop,apache/incubator-tinkerpop