Add CI support on OpenJDK7 and OracleJDK7.
Add CI support on OpenJDK7 and OracleJDK7.

Signed-off-by: Tsuyoshi Ozawa <5f6624a79fc6be19242b6f85a4f5e0138f858769@gmail.com>

jackyglony/msgpack-java,dongjiaqiang/msgpack-java,xuwei-k/msgpack-java,dongjiaqiang/msgpack-java,xuwei-k/msgpack-java,xerial/msgpack-java,DataDog/msgpack-java,msgpack/msgpack-java,msgpack/msgpack-java,suzukaze/msgpack-java,suzukaze/msgpack-java,jackyglony/msgpack-java,xerial/msgpack-java,DataDog/msgpack-java