Fixes depreciated Couchbase REST API URI (couchbase 3.0).

- Fixes depreciated Couchbase REST API URI (Couchbase 3.0).
![depreciated](https://cloud.githubusercontent.com/assets/5708089/5115018/a15278be-700b-11e4-8515-5c8c19d00870.jpg)
- Couchbase 1.8+ support