Resolve "Remove deprecation in flutter gradle plugin"

Closes #67 (closed)

android/app/build.gradle

+plugins {
+    id "com.android.application"
+    id "kotlin-android"
+    id "dev.flutter.flutter-gradle-plugin"
+}
+
 def localProperties = new Properties()
 def localPropertiesFile = rootProject.file('local.properties')
 if (localPropertiesFile.exists()) {
@@ -14,11 +20,6 @@ if (gradlePropertiesFile.exists()) {
     }
 }
 
-def flutterRoot = localProperties.getProperty('flutter.sdk')
-if (flutterRoot == null) {
-    throw new GradleException("Flutter SDK not found. Define location with flutter.sdk in the local.properties file.")
-}
-
 def appVersionCode = gradleProperties.getProperty('app.versionCode')
 if (appVersionCode == null) {
     appVersionCode = '1'
@@ -29,9 +30,6 @@ if (appVersionName == null) {
     appVersionName = '1.0'
 }
 
-apply plugin: 'com.android.application'
-apply from: "$flutterRoot/packages/flutter_tools/gradle/flutter.gradle"
-
 def keystoreProperties = new Properties()
 def keystorePropertiesFile = rootProject.file('key.properties')
 if (keystorePropertiesFile.exists()) {