added a get_metric_history_as_columns method returning metrics history in a columnar format
added a get_metric_history_as_columns method returning metrics history in a columnar format

bradmontgomery/django-redis-metrics,stephanpoetschner/django-redis-metrics,stephanpoetschner/django-redis-metrics,bradmontgomery/django-redis-metrics,stephanpoetschner/django-redis-metrics,bradmontgomery/django-redis-metrics