CBQE-128: refactor view query tests

now tests will use load, query, query verification tasks
Also by this commit added:
* Support of load multiply generators
* MonitorViewQueryResults task: will wait for expected result trying to get it <retries> times
* Allow specifying which server to query and which servers should be checked during index waiting
* Ability to pass pre-generated results to viewQueryVerificationTask
* GenerateViewQueryResultsTask now can generate results for views with reduce fn also

Change-Id: I59923693dee7744fbdfa489fad6c409098435bea
Reviewed-on: http://review.couchbase.org/25072
Reviewed-by: Tommie McAfee <tommie@couchbase.com>
Tested-by: buildbot <build@couchbase.com>