title: add recyclerview and cardview dependencies to gradle module
body: <p>i want to add recyclerview and cardview dependencies to gradle module but it keeps giving error : the library should not use different version(25) then compile sdk version(26) ... i have latest updated android studio sdk version 26... here is code:apply plugin: 'com.android.application'</p>
  
  <pre><code>android {
      compileSdkVersion 26
      buildToolsVersion "26.0.0"
      defaultConfig {
          applicationId "com.dpl_it.m.hamzam.widgets"
          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 {
      compile fileTree(include: ['*.jar'], dir: 'libs')
      androidTestCompile('com.android.support.test.espresso:espresso-core:2.2.2', {
          exclude group: 'com.android.support', module: 'support-annotations'
      })
      compile 'com.android.support:appcompat-v7:26.0.0'
      compile 'com.android.support.constraint:constraint-layout:1.0.2'
      testCompile 'junit:junit:4.12'
      compile 'com.android.support:cardview-v7:25.4.0'
      compile 'com.android.support:recyclerview-v7:25.4.0'
  
  }
  </code></pre>