Implemented GetDataSetsTask and GetOptionSetTask. Implemented coressponding models, managers and converters.
Light refactoring: moved out JsonConverters into separate package.
Light refactoring: Renamed Options to FormOptions in order to make things transparent and simple to understand. Added GetProgramsTask, corresponding JsonConverters and Holders
Added GetDashboardsTask, corresponding models, json converters.
Implemented PostReportTask