Add API 20/Current in the support lib.

Change-Id: Ica5ffad4f3915dbf9af152d1e5e38a1437a804dc
diff --git a/v7/appcompat/build.gradle b/v7/appcompat/build.gradle
index d8aff0c..26a3660 100644
--- a/v7/appcompat/build.gradle
+++ b/v7/appcompat/build.gradle
@@ -7,7 +7,7 @@
 }
 
 android {
-    compileSdkVersion 19
+    compileSdkVersion 'current'
     buildToolsVersion "19.0.1"
 
     sourceSets {