Sign release version of app

android/app/build.gradle

@@ -5,6 +5,12 @@ plugins {
     id "dev.flutter.flutter-gradle-plugin"
 }
 
+def keystoreProperties = new Properties()
+def keystorePropertiesFile = rootProject.file('key.properties')
+if (keystorePropertiesFile.exists()) {
+    keystoreProperties.load(new FileInputStream(keystorePropertiesFile))
+}
+
 android {
     namespace = "de.swgross.calorimeter"
     compileSdk = flutter.compileSdkVersion
@@ -27,11 +33,18 @@ android {
         versionName = "1.0.1"
     }
 
+	signingConfigs {
+        release {
+            keyAlias = keystoreProperties['keyAlias']
+            keyPassword = keystoreProperties['keyPassword']
+            storeFile = keystoreProperties['storeFile'] ? file(keystoreProperties['storeFile']) : null
+            storePassword = keystoreProperties['storePassword']
+        }
+    }
+
     buildTypes {
         release {
-            // TODO: Add your own signing config for the release build.
+            signingConfig = signingConfigs.release
-            // Signing with the debug keys for now, so `flutter run --release` works.
-            signingConfig = signingConfigs.debug
         }
     }
 }