Replace Launcher2 with Launcher3

Launcher2 is deprecated and should use Launcher3, as the latter
can handle higher resolution devices (such as Nexus 6).
Most importantly, Launcher3 is maintained.

Change-Id: I3a80f242af2baaebe90af93794b0ba5e249dbc7d
diff --git a/target/product/core.mk b/target/product/core.mk
index 519dbb8..d27fb8e 100644
--- a/target/product/core.mk
+++ b/target/product/core.mk
@@ -40,7 +40,7 @@
     KeyChain \
     Keyguard \
     LatinIME \
-    Launcher2 \
+    Launcher3 \
     ManagedProvisioning \
     PicoTts \
     PacProcessor \