Modified json types and deserialization in reports. Closes #377

Now all data that come from server is deserialised using  JsonConvert.DeserializeObject. Some data like rate, sum, time entries per project are available for future use. fixes #377
I removed all extra code and tried to keep the call to reports service as simple as possible, the nature of the call is different to others: only to get some data, no sync, no measurements of time, not sensitive data. At this point, if some extra checking is needed just let me know.