Create auto VersionName and VersionCode

build.gradle

def computeVersionName() {
    def stdout = new ByteArrayOutputStream()
    exec {
        commandLine 'git', 'describe', '--abbrev=0', '--tags'
        standardOutput = stdout
    }
    return stdout.toString().trim().replaceAll('v', '')
}

def computeVersionCode() {
    def stdout = new ByteArrayOutputStream()
    exec {
        commandLine 'git', 'rev-list', '--count', 'HEAD'
        standardOutput = stdout
    }
    return stdout.toString().trim().toInteger()
}