CBIDXT-229: DP4 integration with cbq-bridge and indexer.

- renamed IndexInfo:OnExprList to IndexInfo:SecExprs.
- renamed IndexInfo:Uuid to IndexInfo:DefnID.
- removed ServerUuid from cbq_bridge.
- modified cbq_bridge_defs.go to match IndexInfo, IndexRequest,
  IndexMetaResponse with queryport's cluster_client.go.
  - removed NOTIFY, NODES, SCAN, STATS
  - removed QueryParams, IndexRow, IndexScanResponse, NodeInfo,
- under manager/
  - minor go-formatting on comments.
  - changed OnExprList to SecExprs.
  - match IndexInfo structure with cbq_bridge.

TODO:
- identical structures are maintained by indexer/ queryport/ and manager/,
  will have to consolidate them into a common place.
- cbq_bridge is using indexMap which is a maps of,
    indexMap:   make(map[common.IndexInstId]IndexInfo),
  `DefnID` is now treated as instance-id. Is that OKAY ?

Change-Id: I1a21cb1051d80c80be570e7b92918b278461b8b7
Reviewed-on: http://review.couchbase.org/43173
Reviewed-by: John Liang <johliang00@gmail.com>
Reviewed-by: Pratap Chakravarthy <prataprc@couchbase.com>
Tested-by: Pratap Chakravarthy <prataprc@couchbase.com>