Added delete subscription method to IFitbitClient interface
Added delete subscription method to IFitbitClient interface

amammay/Fitbit.NET,amammay/Fitbit.NET,aarondcoleman/Fitbit.NET,WestDiscGolf/Fitbit.NET,AlexGhiondea/Fitbit.NET,WestDiscGolf/Fitbit.NET,aarondcoleman/Fitbit.NET,AlexGhiondea/Fitbit.NET,AlexGhiondea/Fitbit.NET,amammay/Fitbit.NET,WestDiscGolf/Fitbit.NET,aarondcoleman/Fitbit.NET