Add a hash function for bluetooth addresses

Also includes simple tests for it + disambiguates
including hash_function.h throughout the stack.
diff --git a/btcore/Android.mk b/btcore/Android.mk
index c3f78b8..a9a7795 100644
--- a/btcore/Android.mk
+++ b/btcore/Android.mk
@@ -49,6 +49,7 @@
     $(LOCAL_PATH)/..
 
 LOCAL_SRC_FILES := \
+    ./test/bdaddr_test.cpp \
     ./test/counter_test.cpp \
     ../osi/test/AllocationTestHarness.cpp