Upgrade OkHttp to 2.5
diff --git a/build.gradle b/build.gradle
index 297f443..717ea3c 100644
--- a/build.gradle
+++ b/build.gradle
@@ -130,7 +130,7 @@
                 jsonp: 'org.glassfish:javax.json:1.0.4',
                 jsr305: 'com.google.code.findbugs:jsr305:3.0.0',
                 oauth_client: 'com.google.auth:google-auth-library-oauth2-http:0.3.0',
-                okhttp: 'com.squareup.okhttp:okhttp:2.4.0',
+                okhttp: 'com.squareup.okhttp:okhttp:2.5.0',
                 protobuf: "com.google.protobuf:protobuf-java:${protobufVersion}",
                 protobuf_nano: "com.google.protobuf.nano:protobuf-javanano:${protobufNanoVersion}",
                 protobuf_plugin: 'com.google.protobuf:protobuf-gradle-plugin:0.7.0',