Version bump to OPD1.170731.002

Change-Id: Idebdcf72dc98d4aba6398e009a485c0c4f635f6f
diff --git a/core/build_id.mk b/core/build_id.mk
index c35b4a5..53a4576 100644
--- a/core/build_id.mk
+++ b/core/build_id.mk
@@ -18,4 +18,4 @@
 # (like "CRB01").  It must be a single word, and is
 # capitalized by convention.
 
-export BUILD_ID=OPD1.170731.001
+export BUILD_ID=OPD1.170731.002