CBQE-1902: CBRecoveryTask implementation

Change-Id: I72df9dba2493780b378b6a0e5c817ca2ca1c52d3
Reviewed-on: http://review.couchbase.org/33240
Reviewed-by: Iryna Mironava <irynamironava@yandex.ru>
Tested-by: buildbot <build@couchbase.com>