Keep the emma classes if emma is enabled.

Change-Id: Ie551d48532c61bf610b12875dc33cfe476625c5e
diff --git a/core/proguard.emma.flags b/core/proguard.emma.flags
new file mode 100644
index 0000000..bf94086
--- /dev/null
+++ b/core/proguard.emma.flags
@@ -0,0 +1,4 @@
+# Keep everything for the emma classes
+-keep class com.vladium.** {
+  *;
+}