Couchbase 2.0.1

Hello!

This is one of two optional pull requests, and if neither will work, I can publish separately. This branch moves your module to the 'Couchbase' module on CPAN, which replaces the deprecated Couchbase::Client. Furthermore, it moves the session store types (session/expires/flash) into one document to save on key space. I have another branch available that is just the Couchbase migration without the merging into one document, if that seems needlessly complex for your module, and I can create a pull request with that one instead.

The additional unit test only covers the connection url builder.

Comments and questions are welcome.