Make Dialer a core app

Set coreApp="true" in AndroidManifest so emergency calls work from lock screen
on encrypted phones.

Bug:13586583
Change-Id: I1065743cae4c2090351226de193751606fde1b51
diff --git a/AndroidManifest.xml b/AndroidManifest.xml
index 3a643a8..509960c 100644
--- a/AndroidManifest.xml
+++ b/AndroidManifest.xml
@@ -15,7 +15,8 @@
 -->
 
 <manifest xmlns:android="http://schemas.android.com/apk/res/android"
-    package="com.android.dialer">
+    package="com.android.dialer"
+    coreApp="true">
 
     <uses-permission android:name="android.permission.CALL_PRIVILEGED" />
     <uses-permission android:name="android.permission.READ_CONTACTS" />