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
Maybe use `Int32.TryParse(...)` instead of doing `IsNullOrEmpty` check.. just to be sure should the API screw up and return say "blue" for color we don't crash.