change duplicates strategy to avoid
duplicate files in META-INFO folder,and also exclude maven folder in META-INFO.
add two tasks named with proguard and proguardCheck.Task proguard uses proguard tool to shrinking the uberjar.The size is reduced from 8M to 4.6M.
Of course here are more thing we can do to make a smaller jar and proguardCheck is a way to run test with the package jar.Be relax to change proguard.pro settings and use proguardCheck to check it works well or not.
remove duplicate part
fix rt.jar not found error in mac and more detail setting with proguard.
merged pull request #53
removed configuration from wrapper task and used gradle.properties config