Add replication selector support.

[smithsz]

Checklist

• [x] Tick to sign-off your agreement to the Developer Certificate of Origin (DCO) 1.1
• [x] Added tests for code changes or test/build only changes
• [x] Updated the change log file (CHANGES.md|CHANGELOG.md) or test/build only changes
• [x] Completed the PR template below:

Description

Add replication selector support.

client.replicator()
                     .replicatorDocId(replicatorDocId)
                     .source(sourceDbUrl)
                     .target(targetDbUrl)
                     .selector(eq("_id", "Schwarzenegger"))
                     .save();

Fixes #477.

Approach

Added selector option to Replicator builder.

Schema & API Changes

Additional getters/setters.

Security and Privacy

No change.

Testing

Additional mock test.

Monitoring and Logging