Build tools to 24.0.2 in AntennaPod

Update the build tools version that is now the
minimum one required to run the new plugin.

Change-Id: I710b30a4e55daefa9480bda6016eee2dcc7610b1
diff --git a/build.gradle b/build.gradle
index b3a0b29..111d4e9 100644
--- a/build.gradle
+++ b/build.gradle
@@ -41,7 +41,7 @@
 
 project.ext {
     compileSdkVersion = 23
-    buildToolsVersion = "23.0.2"
+    buildToolsVersion = "24.0.2"
     minSdkVersion = 10
     targetSdkVersion = 23