[MIGRATION] Added a cache::review_stats model so that the organization index action doesn't need to compute everything on the fly - issue #4
Made update_cache into a bang method
Added with_condition scope to the review model
Made it so that update_cache calculates the num_review and avg_review
Basic functionality of the update_cache! method in the review model
Call update_cache when a review is destroyed
Calling update_cache twice if the condtion_id changed
Prevent the cache review stat average from being nil
Making the ordering of the organizations based on the review cache
Using the cache value in the organizatoin table
Make it so that the ratings are sorted first and then by distance if applicable
Merge branch 'cache_stats'