Issue Description: Nifi Couchbase processors don't work with new couchbase versions 5.0 and 5.1.
New Couchbase Version 5.x has introduced Role Based Access Control (RBAC), a ** new security feature.
- All buckets must now be accessed by a user/password combination that has a role with access rights to the bucket.
- Buckets no longer use bucket-level passwords
- There is no default bucket and no sample buckets with blank passwords.
- You cannot create a user without a password.
nifi-couchbase-processors : GetCouchbaseKey and PutCouchbaseKey using Controller Service still uses old authentication mechanism.