Go-XDCR: Able to create replication on/to non-existing buckets

This was a case where default and target buckets were not present in the cluster.
Looks like we are able to persist replication spec regardless of whether buckets exist. I'm not sure if this will be handled by ns_server.

Arunas-MacBook-Pro:sherlock apiravi$ curl -X POST http://localhost:12100/controller/createReplication -d fromBucket=default -d uuid=localhost:9000 -d toBucket=target -d filterName=filter2 -d xdcrLogLevel=Debug -d xdcrFilterExpression=new.
id=xdcr_127.0.0.1%3A9000_default_localhost%3A9000_target_filter2

Http server log
-------------------

ReplicationManager13:38:45.581200 [INFO] Creating replication spec - sourceCluterUUID=127.0.0.1:9000, sourceBucket=default, targetClusterUUID=localhost:9000, targetBucket=target, filterName=filter2, settings=map[http_connection:20 max_expected_replication_lag:1000 filter_expression:new. timeout_percentage_cap:80 log_level:Debug source_nozzle_per_node:2 batch_count:500 optimistic_replication_threshold:256 active:true replication_type: checkpoint_interval:1800 target_nozzle_per_node:2 batch_size:2048 failure_restart_interval:30]
ReplicationManager13:38:45.584120 [INFO] Pipeline xdcr_127.0.0.1:9000_default_localhost:9000_target_filter2 is created and started
AdminPort13:38:45.584128 [INFO] forwardReplicationRequest
PipelineManager13:38:45.584165 [INFO] Starting the pipeline xdcr_127.0.0.1:9000_default_localhost:9000_target_filter2
XDCRFactory13:38:45.584634 [INFO] kvHosts=[127.0.0.1]
cluster=127.0.0.1:9000
XDCRFactory13:38:45.587276 [ERROR] err=Error getting pool with name 'default'.
No pool named default
PipelineManager13:38:45.587288 [ERROR] Failed to construct a new pipeline: Error getting pool with name 'default'.
No pool named default