LogIgnore() to ignore logs while unit-testing.

Change-Id: I74c3ec4c986df3c4aab10ab2df6159ab4837cefe
Reviewed-on: http://review.couchbase.org/39047
Reviewed-by: Deepkaran Salooja <deepkaran.couchbase@gmail.com>
Reviewed-by: Pratap Chakravarthy <prataprc@couchbase.com>
Tested-by: Pratap Chakravarthy <prataprc@couchbase.com>