Update protobuf-gradle-plugin to 0.8.3

This fixes support for newer Android Gradle Plugins.
diff --git a/README.md b/README.md
index 080c441..a31dd6b 100644
--- a/README.md
+++ b/README.md
@@ -117,7 +117,7 @@
   dependencies {
     // ASSUMES GRADLE 2.12 OR HIGHER. Use plugin version 0.7.5 with earlier
     // gradle versions
-    classpath 'com.google.protobuf:protobuf-gradle-plugin:0.8.1'
+    classpath 'com.google.protobuf:protobuf-gradle-plugin:0.8.3'
   }
 }
 
diff --git a/android-interop-testing/build.gradle b/android-interop-testing/build.gradle
index 819c1f8..99d37fd 100644
--- a/android-interop-testing/build.gradle
+++ b/android-interop-testing/build.gradle
@@ -6,7 +6,7 @@
     }
     dependencies {
         classpath 'com.android.tools.build:gradle:2.3.1'
-        classpath "com.google.protobuf:protobuf-gradle-plugin:0.8.1"
+        classpath "com.google.protobuf:protobuf-gradle-plugin:0.8.3"
 
         // NOTE: Do not place your application dependencies here; they belong
         // in the individual module build.gradle files
diff --git a/build.gradle b/build.gradle
index 48b76b4..d31086f 100644
--- a/build.gradle
+++ b/build.gradle
@@ -205,7 +205,7 @@
                 protobuf_lite: "com.google.protobuf:protobuf-lite:3.0.1",
                 protoc_lite: "com.google.protobuf:protoc-gen-javalite:3.0.0",
                 protobuf_nano: "com.google.protobuf.nano:protobuf-javanano:${protobufNanoVersion}",
-                protobuf_plugin: 'com.google.protobuf:protobuf-gradle-plugin:0.8.1',
+                protobuf_plugin: 'com.google.protobuf:protobuf-gradle-plugin:0.8.3',
                 protobuf_util: "com.google.protobuf:protobuf-java-util:${protobufVersion}",
 
                 netty: "io.netty:netty-codec-http2:[${nettyVersion}]",
diff --git a/examples/android/clientcache/build.gradle b/examples/android/clientcache/build.gradle
index be0b49f..6f6011c 100644
--- a/examples/android/clientcache/build.gradle
+++ b/examples/android/clientcache/build.gradle
@@ -6,7 +6,7 @@
     }
     dependencies {
         classpath 'com.android.tools.build:gradle:2.3.1'
-        classpath "com.google.protobuf:protobuf-gradle-plugin:0.8.1"
+        classpath "com.google.protobuf:protobuf-gradle-plugin:0.8.3"
 
         // NOTE: Do not place your application dependencies here; they belong
         // in the individual module build.gradle files
diff --git a/examples/android/helloworld/build.gradle b/examples/android/helloworld/build.gradle
index be0b49f..6f6011c 100644
--- a/examples/android/helloworld/build.gradle
+++ b/examples/android/helloworld/build.gradle
@@ -6,7 +6,7 @@
     }
     dependencies {
         classpath 'com.android.tools.build:gradle:2.3.1'
-        classpath "com.google.protobuf:protobuf-gradle-plugin:0.8.1"
+        classpath "com.google.protobuf:protobuf-gradle-plugin:0.8.3"
 
         // NOTE: Do not place your application dependencies here; they belong
         // in the individual module build.gradle files
diff --git a/examples/android/routeguide/build.gradle b/examples/android/routeguide/build.gradle
index d0f785a..316dc9d 100644
--- a/examples/android/routeguide/build.gradle
+++ b/examples/android/routeguide/build.gradle
@@ -6,7 +6,7 @@
     }
     dependencies {
         classpath 'com.android.tools.build:gradle:2.3.1'
-        classpath "com.google.protobuf:protobuf-gradle-plugin:0.8.1"
+        classpath "com.google.protobuf:protobuf-gradle-plugin:0.8.3"
 
         // NOTE: Do not place your application dependencies here; they belong
         // in the individual module build.gradle files
diff --git a/examples/build.gradle b/examples/build.gradle
index c2703bd..5bf7c5a 100644
--- a/examples/build.gradle
+++ b/examples/build.gradle
@@ -8,7 +8,7 @@
   dependencies {
     // ASSUMES GRADLE 2.12 OR HIGHER. Use plugin version 0.7.5 with earlier
     // gradle versions
-    classpath 'com.google.protobuf:protobuf-gradle-plugin:0.8.1'
+    classpath 'com.google.protobuf:protobuf-gradle-plugin:0.8.3'
   }
 }