Implement aggregation when add_metric is called for the same metric more than once in a request
Completed implementation of aggregation, context now returns the appropriate request to enable aggregation when a request is not successfully sent to the collector
Implemented some code improvements that were suggested in review
fixing order of metric array to match http api, this would not have caused issues before the implementation of aggregation
Merge pull request #25 from newrelic-platform/nathan/aggregation

Adding aggregation to the Ruby SDK