Per a conversation with :wlach, the usage of signature_hash should be deprecated and removed in Perfherder - in the
graphs controller and
comparesubtestdistribution replicates controller. However, this might require versioning changes to
performance/datum since the returned data is designed to be accessed by hash key.
If signature_hash can be replaced then the compare view 'graph' and
comparesubtest view 'replicate' urls should also replace the
signature_hash query param with
signature_id (currently PerformanceDatum has 'id', PerformanceSignature has 'signature_id').