无法将 Firebase Crashlytics 连接到项目

再会。我想连接到 Crashlytics 项目，我跟着办公室。指令但抛出错误：

Error:Execution failed for task ':app:processDebugGoogleServices'.
> Please fix the version conflict either by updating the version of the google-services plugin (information about the latest version is available at https://bintray.com/android/android-tools/com.google.gms.google-services/) or updating the version of com.google.android.gms to 11.4.2.

我无法弄清楚版本不兼容的确切位置。build.gradle 项目代码

buildscript {
    repositories {
        google()
        jcenter()
        mavenCentral()
        maven {
            url 'https://maven.fabric.io/public'
        }
    }
    dependencies {
        classpath 'com.android.tools.build:gradle:3.0.1'
        classpath 'com.jakewharton:butterknife-gradle-plugin:8.8.1'

        classpath 'com.google.gms:google-services:3.1.2'
        classpath 'io.fabric.tools:gradle:1.24.4'
    }
}

allprojects {
    repositories {
        google()
        jcenter()
        maven {
            url 'https://maven.google.com/'
        }
    }
}

task clean(type: Delete) {
    delete rootProject.buildDir
}

build.gradle 应用代码

apply plugin: 'com.android.application'
apply plugin: 'com.google.gms.google-services'
apply plugin: 'io.fabric'

android {
    compileSdkVersion 26
    defaultConfig {
        applicationId "tanat.androidtesttask"
        minSdkVersion 15
        targetSdkVersion 26
        versionCode 1
        versionName "1.0"
        testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
    }
    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
        }
    }
}

dependencies {
    implementation fileTree(dir: 'libs', include: ['*.jar'])
    implementation 'com.android.support:appcompat-v7:26.1.0'
    implementation 'com.android.support.constraint:constraint-layout:1.0.2'
    implementation 'com.android.support:support-v4:26.1.0'
    implementation 'com.android.support:recyclerview-v7:26.1.0'
    testImplementation 'junit:junit:4.12'
    androidTestImplementation 'com.android.support.test:runner:1.0.1'
    androidTestImplementation 'com.android.support.test.espresso:espresso-core:3.0.1'

    implementation 'com.jakewharton:butterknife:8.8.1'
    annotationProcessor 'com.jakewharton:butterknife-compiler:8.8.1'

    compile('com.crashlytics.sdk.android:crashlytics:2.7.1@aar') {
        transitive = true
    }
    compile 'com.google.firebase:firebase-core:11.8.0'
}

请帮我找到解决方案。