Build SlimFileManager

and remove old one.

Change-Id: I95c59fb79a5ab9cc262a9689dde747b663255bb7
diff --git a/config/common.mk b/config/common.mk
index 217a163..48b1820 100644
--- a/config/common.mk
+++ b/config/common.mk
@@ -142,7 +142,7 @@
 # Extra Optional packages
 PRODUCT_PACKAGES += \
     HoloLauncherHD \
-    FileManager \
+    SlimFileManager \
     Velvet \
     LatinIME