Build against the ICS mr1 SDK

Change-Id: I24276cdb7fd9f62aeddc29287615f2494d2a9de2
diff --git a/exchange2/Android.mk b/exchange2/Android.mk
index 24aba9a..39c320b 100644
--- a/exchange2/Android.mk
+++ b/exchange2/Android.mk
@@ -29,6 +29,7 @@
 LOCAL_OVERRIDES_PACKAGES := Exchange
 
 LOCAL_PROGUARD_FLAG_FILES := proguard.flags
+LOCAL_SDK_VERSION := 15
 
 LOCAL_EMMA_COVERAGE_FILTER += +com.android.exchange.*