Fix L3 and old Trebuchet migration

There can only be one original-package tag. Go with com.android.launcher3
for now, and move Trebuchet back to com.cyanogenmod.trebuchet. This will
allow for workspace migrations from both CM10.2 Trebuchet and from CM11
Launcher3

Change-Id: I7743954bffc55f503851038f800607947e20015e