The release date is a property of a data point, not of a timeseries.
The release date is a property of a data point, not of a timeseries.

Closes #12

mmalter/dlstats,MichelJuillard/dlstats,Widukind/dlstats,mmalter/dlstats,MichelJuillard/dlstats,mmalter/dlstats,MichelJuillard/dlstats,Widukind/dlstats