Fix 1

ENCAPSULATION OF ObservationSeries
- Moved fetchDataSeries method to class ObservationSeries
- Added getObservations method

Fixed Observation object to use dates instead of date time

ENCAPSULATION OF Scarecrow
- Scarecrow should be running calculations ON ObservationSeries. The
ObservationSeries class should be simple data members and their
necessary interactions (fetch,plot).