Ensure free_client() method is called on connection retries.

We need to explicitly call free_client within the retry loop, as the ensure section is only called once, on resque block exit.
Make node role verification optional via :verify_role option. Gets rid of redundant INFO query before every redis operation.
Merge pull request #57 from fanhattan/free_client-retry-fix

Make sure free_client() method is called on connection retries.
Merge pull request #58 from fanhattan/verify_role-optional

Make node role verification optional via :verify_role option.
Merge pull request #4 from ryanlecompte/master

Pull in changes from upstream repo.