Removed aggregator behaviour from MetricResult
Fixes for rebased version of MetricAggregator
Removed unnecessary trait
Renamed MetricAggregator to MetricResultAggregator
Removed unecessary before :each block do MetricResultAggregator spec
Removed unnecessary expectation from Aggregator spec
Merge pull request #59 from mezuro/metric_result_refactoring

Removed aggregator behaviour from MetricResult