Improvement to #5254

- Do not check on the writer name, only the presence, type, and
  availability of the "db" option value.

  See https://github.com/zendframework/zf2/pull/5254#issuecomment-27776073
Merging PR #5588
Merge branch 'weierophinney-hotfix/5254-improvement'

* weierophinney-hotfix/5254-improvement:
  Improvement to #5254