Implemented MetricMapper#create
Implemented MetricMapper#find_by_name
Implemented MetricMapper#find_or_create_by_name
Refactored MetricMapper spec
Added TwitterSensor
Scoped Metric properly
Require submodules
Implemented MetricMapper#count
First version of TwitterSensor#take_measurements
Added Measurement
Added metric field to Measurement
Measurement has no conception of metric_ids
Added the MeasurementMapper