Add ro.revision property to checkin headers

Early hardware revisions often have known issues.  Add the ro.revision
property to the header for the checkin reports so known issues can
be easily filtered.

Change-Id: I337b09ddfa41ebbe7f8f56223392b0bd491f897b
diff --git a/services/java/com/android/server/BootReceiver.java b/services/java/com/android/server/BootReceiver.java
index 22874e6..7e1de5a 100644
--- a/services/java/com/android/server/BootReceiver.java
+++ b/services/java/com/android/server/BootReceiver.java
@@ -88,6 +88,8 @@
         final String headers = new StringBuilder(512)
             .append("Build: ").append(Build.FINGERPRINT).append("\n")
             .append("Hardware: ").append(Build.BOARD).append("\n")
+            .append("Revision: ")
+            .append(SystemProperties.get("ro.revision", "")).append("\n")
             .append("Bootloader: ").append(Build.BOOTLOADER).append("\n")
             .append("Radio: ").append(Build.RADIO).append("\n")
             .append("Kernel: ")