Fixing gradle version comflicts

Change-Id: I6e3b99e2ad67a192e29f9939fc188db81f31d219
diff --git a/build.gradle b/build.gradle
index 2306744..1956178 100644
--- a/build.gradle
+++ b/build.gradle
@@ -3,7 +3,7 @@
         mavenCentral()
     }
     dependencies {
-        classpath 'com.android.tools.build:gradle:+'
+        classpath 'com.android.tools.build:gradle:1.5.0'
         classpath 'com.google.protobuf:protobuf-gradle-plugin:0.7.0'
     }
 }