Refactor responder into its own method

Also add another responder to simulate 401 response
Issue #241 - add test to detect missing feature

https://github.com/couchbase/couchbase-lite-android/issues/241
Rename variable
Issue #269 - unit test for PersistentCookieStore

https://github.com/couchbase/couchbase-lite-android/issues/269

Issue #269 - implement additional methods for HttpClientFactory

https://github.com/couchbase/couchbase-lite-android/issues/269
Merge pull request #273 from couchbase/feature/issue_269_squashed_persist_cookie

Feature/issue 269 squashed persist cookie