CBQE-1791: adding sleep between reboot and wait for reboot

Change-Id: I1e8b3c5c8ff8f6218015b88777675fad41143236
Reviewed-on: http://review.couchbase.org/31224
Reviewed-by: Sangharsh Agarwal <sangharsh.agarwal@globallogic.com>
Tested-by: Sangharsh Agarwal <sangharsh.agarwal@globallogic.com>