Error:(26, 0) Gradle DSL method not found: 'runProguard()' Ask Question

I'm using android studio 0.9.3 with gradle 'com.android.tools.build:gradle:0.14.+'

apply plugin: 'com.android.application'

android {
    compileSdkVersion 19
    buildToolsVersion '20.0.0'

    defaultConfig {
        applicationId "xxx.xxx.xxx"
        minSdkVersion 16
        targetSdkVersion 19
        versionCode 1
        versionName "1.0.11"
    }

    signingConfigs{
        releaseConfig{
            storeFile file("xxxxxxx")
            storePassword = "xxxx"
            keyAlias = "xxxx"
            keyPassword = "xxxx"
        }
    }

    buildTypes {
        release {
            runProguard false
            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
            signingConfig signingConfigs.releaseConfig

            // adds version to file name
            applicationVariants.all { variant ->
                def file = variant.outputFile
                variant.outputFile = new File(file.parent, file.name.replace(".apk", "-" + defaultConfig.versionName + ".apk"))
            }
        }
    }
}

dependencies {
    compile fileTree(dir: 'libs', include: ['*.jar'])
    // You must install or update the Support Repository through the SDK manager to use this dependency.
    // You must install or update the Support Repository through the SDK manager to use this dependency.
    // You must install or update the Google Repository through the SDK manager to use this dependency.
    // You must install or update the Support Repository through the SDK manager to use this dependency.
    compile 'com.android.support:support-v4:19.+'
    compile 'com.android.support:appcompat-v7:19.+'
    compile 'com.mcxiaoke.volley:library:1.0.6'
    compile 'com.google.code.gson:gson:2.2.+'
}