Added Ever thing for app signing and added a basic icon (#2)

Added App Signing and Basic Icon

Signed-off-by Andreas Fahrecker <AndreasFahrecker@gmail.com>

android/app/build.gradle

@@ -25,6 +25,12 @@ apply plugin: 'com.android.application'
 apply plugin: 'kotlin-android'
 apply from: "$flutterRoot/packages/flutter_tools/gradle/flutter.gradle"
 
+def keystoreProperties = new Properties()
+def keystorePropertiesFile = rootProject.file('key.properties')
+if (keystorePropertiesFile.exists()) {
+    keystoreProperties.load(new FileInputStream(keystorePropertiesFile))
+}
+
 android {
     compileSdkVersion 28
 
@@ -40,16 +46,23 @@ android {
         // TODO: Specify your own unique Application ID (https://developer.android.com/studio/build/application-id.html).
         applicationId "com.fahrecker.time_progress_calculator"
         minSdkVersion 16
-        targetSdkVersion 28
+        targetSdkVersion 29
         versionCode flutterVersionCode.toInteger()
         versionName flutterVersionName
     }
 
+    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.
-            // Signing with the debug keys for now, so `flutter run --release` works.
-            signingConfig signingConfigs.debug
+            signingConfig signingConfigs.release
         }
     }
 }