Update plugin template to new channel API. (#9105)

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

@@ -30,3 +30,7 @@ android {
         disable 'InvalidPackage'
     }
 }
+
+dependencies {
+    compile 'com.android.support:support-fragment:25.0.0'
+}

packages/flutter_tools/templates/plugin/android.tmpl/src/main/java/com/yourcompany/projectName/pluginClass.java.tmpl

@@ -29,7 +29,7 @@ public class {{pluginClass}} implements MethodCallHandler {
     if (call.method.equals("getPlatformVersion")) {
       response.success("Android " + android.os.Build.VERSION.RELEASE);
     } else {
-      throw new IllegalArgumentException("Unknown method " + call.method);
+      response.notImplemented();
     }
   }
 }

packages/flutter_tools/templates/plugin/ios.tmpl/Classes/pluginClass.m.tmpl

@@ -7,15 +7,13 @@
   self = [super init];
   if (self) {
     FlutterMethodChannel *channel = [FlutterMethodChannel
-        methodChannelNamed:@"{{projectName}}"
-           binaryMessenger:flutterView
-                     codec:[FlutterStandardMethodCodec sharedInstance]];
+        methodChannelWithName:@"{{projectName}}"
+           binaryMessenger:flutterView];
     [channel setMethodCallHandler:^(FlutterMethodCall *call,
                                     FlutterResultReceiver result) {
       if ([@"getPlatformVersion" isEqualToString:call.method]) {
         result([@"iOS " stringByAppendingString:[[UIDevice currentDevice]
-                                                    systemVersion]],
-               nil);
+                                                    systemVersion]]);
       }
     }];
   }