don't deepcopy options

If you pass in a redis connection pool and have Leaderboard deepcopy it
each init it will have major performance degradation.
Fix page_for with ordering

* Need to use zrank in the case of lowest-to-highest (order: ASC) ranking
* Fix tests to correctly test for this bug
* Fixes #6
Merge pull request #5 from simonz05/performance

don't deepcopy options
Fix tests to actually test for equality