Create buckets for unit tests

For the unit tests to run, the following buckets must be created:

• 'default'
  • couchbase
  • ~400mb size
  • replicas: 3 (assume a 4 node cluster)
• 'authenticated'
  • couchbase
  • password: 'secret'
  • ~100mb size
• 'memcached'
  • ~100mb size
  • memcached bucket
• 'beer-sample' installed
• 'travel-sample' installed