Bump ASOP Contacts version to 1.5.6

Bug:28880104
Change-Id: Ida44609858563456410323291bc9f19b636764bd
diff --git a/AndroidManifest.xml b/AndroidManifest.xml
index 72004a4..7e84ba9 100644
--- a/AndroidManifest.xml
+++ b/AndroidManifest.xml
@@ -16,8 +16,8 @@
 
 <manifest xmlns:android="http://schemas.android.com/apk/res/android"
     package="com.android.contacts"
-    android:versionCode="10505"
-    android:versionName="1.5.5">
+    android:versionCode="10506"
+    android:versionName="1.5.6">
 
     <uses-sdk android:minSdkVersion="21" android:targetSdkVersion="24" />