Refactor RateLimiter so that if Redis is not running, everything still runs normally (minus the rate limiting protection). My assumption that creating a Redis connection would throw an exception if Redis wasn't running was wrong. The exceptions actually occur when you issue a command. This is for #224.

[
    {
        "pk": 1, 
        "model": "oembed.provider", 
        "fields": {
            "api_endpoint": "http://www.youtube.com/oembed", 
            "name": "YouTube", 
            "url_regex": "^http://www\\.youtube\\.com/watch\\?v=\\S+$", 
            "format": 0
        }
    }
]