small test tweaks
Merge branch 'master' of github.com:mje113/couchbase-jruby-client

* 'master' of github.com:mje113/couchbase-jruby-client:
  Allow for false/nil values to be set by #fetch by relying only on the NotFound exception
  Add a #fetch operation
Trying CB 2.2.0 for travis again