Update templates to include google's maven repository (#10842)

Going forward, Android support libraries are published on maven (instead of bundling them with the SDK). Many plugins depend on these. To avoid requiring plugin users to add the maven repository to their app this change adds the repository to the template for `flutter create`.

This also bumps the support-annotations dependency to 25.4.0 (which also requires the new maven repository).

packages/flutter_tools/templates/create/android-java.tmpl/app/build.gradle.tmpl

@@ -43,7 +43,7 @@ flutter {
 }
 
 dependencies {
-    androidTestCompile 'com.android.support:support-annotations:25.0.0'
+    androidTestCompile 'com.android.support:support-annotations:25.4.0'
     androidTestCompile 'com.android.support.test:runner:0.5'
     androidTestCompile 'com.android.support.test:rules:0.5'
 }

packages/flutter_tools/templates/create/android-java.tmpl/build.gradle

@@ -11,6 +11,9 @@ buildscript {
 allprojects {
     repositories {
         jcenter()
+        maven {
+            url "https://maven.google.com"
+        }
     }
 }
 

packages/flutter_tools/templates/create/android-kotlin.tmpl/app/build.gradle.tmpl

@@ -48,7 +48,7 @@ flutter {
 }
 
 dependencies {
-    androidTestCompile 'com.android.support:support-annotations:25.0.0'
+    androidTestCompile 'com.android.support:support-annotations:25.4.0'
     androidTestCompile 'com.android.support.test:runner:0.5'
     androidTestCompile 'com.android.support.test:rules:0.5'
     compile 'org.jetbrains.kotlin:kotlin-stdlib-jre7:1.1.2-4'

packages/flutter_tools/templates/create/android-kotlin.tmpl/build.gradle

@@ -12,6 +12,9 @@ buildscript {
 allprojects {
     repositories {
         jcenter()
+        maven {
+            url "https://maven.google.com"
+        }
     }
 }
 

packages/flutter_tools/templates/plugin/android-java.tmpl/build.gradle.tmpl

@@ -14,6 +14,9 @@ buildscript {
 allprojects {
     repositories {
         jcenter()
+        maven {
+            url "https://maven.google.com"
+        }
     }
 }
 

packages/flutter_tools/templates/plugin/android-kotlin.tmpl/build.gradle.tmpl

@@ -14,6 +14,9 @@ buildscript {
 allprojects {
     repositories {
         jcenter()
+        maven {
+            url "https://maven.google.com"
+        }
     }
 }