CBQE-0: improvements in autofailovertests.py

changes will simplify the transition to inherit from basetestcase

Change-Id: I2cdfba5b7e76f9b0bd3aaacee4e4db228084fc3f
Reviewed-on: http://review.couchbase.org/33254
Reviewed-by: Andrei Baranouski <andrei.baranouski@gmail.com>
Tested-by: Andrei Baranouski <andrei.baranouski@gmail.com>