增加Free的CI配置
Merge pull request #6 from JoeCao/master

将CobarClient加入持续集成https://travis-ci的管理
Update .travis.yml

尝试不同的jdk编译
Merge branch 'cobarclient-2.0' of https://github.com/alibaba/cobarclient
update java to 1.7 to make JDK7 mandatory
change java_source/target back to 1.5 to keep backward compalibility
Merge branch 'cobarclient-2.0' of https://github.com/alibaba/cobarclient into cobarclient-2.0