add signConfig for release build

app/build.gradle

@@ -17,12 +17,25 @@ android {
 
     vectorDrawables.useSupportLibrary = true
   }
+  signingConfigs {
+    release {
+      storeFile project.rootProject.file('Rocket.jks').getCanonicalFile()
+      storePassword System.getenv("KEYSTORE_PASSWORD")
+      keyAlias System.getenv("KEY_ALIAS")
+      keyPassword System.getenv("KEY_PASSWORD")
+    }
+  }
   buildTypes {
     release {
       minifyEnabled false
       proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
+      signingConfig signingConfigs.release
     }
   }
+  packagingOptions {
+    exclude 'META-INF/LICENSE.txt'
+    exclude 'META-INF/NOTICE.txt'
+  }
   compileOptions {
     sourceCompatibility JavaVersion.VERSION_1_8
     targetCompatibility JavaVersion.VERSION_1_8