title: Can't start a new project because of gradle error
body: <p>I created a new project as usual andafter the gradle running I get this error:
  `Error:Execution failed for task ':app:preDebugAndroidTestBuild'.</p>
  
  <blockquote>
    <p>Conflict with dependency 'com.android.support:support-annotations' in project ':app'. Resolved versions for app (26.1.0) and test app (27.1.1) differ. See <a href="https://d.android.com/r/tools/test-apk-dependency-conflicts.html" rel="nofollow noreferrer">https://d.android.com/r/tools/test-apk-dependency-conflicts.html</a> for details.`</p>
  </blockquote>
  
  <p>This is my fresh project gradle:</p>
  
  <pre><code>apply plugin: 'com.android.application'
  
  android {
  compileSdkVersion 26
  defaultConfig {
      applicationId "com.example.elili.deltacalculator"
      minSdkVersion 18
      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:1.1.0'
  testImplementation 'junit:junit:4.12'
  androidTestImplementation 'com.android.support.test:runner:1.0.2'
  androidTestImplementation 'com.android.support.test.espresso:espresso-core:3.0.2'
  </code></pre>
  
  <p>I have zero ideas on how to fix it...</p>