BufferRelocation test: fixes

- Increase timeout for slower systems
- Don't unhiccup nodes until failover has completed. This breaks IOCP
  tests otherwise (where the command suceeds before the failover
happens)
Change-Id: I9700693b581e64815a691cdbe9d78bc09d40b17d
Reviewed-on: http://review.couchbase.org/33001
Reviewed-by: Brett Lawson <brett19@gmail.com>
Tested-by: Mark Nunberg <mnunberg@haskalah.org>