Change 3.0.1 manifest to point to ep-engine 3.0.1 branch

Change-Id: Ia435e2af7b3e6b0d3876d3013a765a46cbbcfb1f
Reviewed-on: http://review.couchbase.org/41197
Reviewed-by: Michael Wiederhold <mike@couchbase.com>
Tested-by: Michael Wiederhold <mike@couchbase.com>