Add detailed error information for exceptions #24
We should unify the exception in RESTier. That is to say if LINQ expression or EF throws an exception. RESTier should wrap it and throw proper exception or return correct status code instead of just leaking the exception to end user.
As an example, #47 shows a duration-related exception thrown by EF. In this case, we should catch it and return 4XX bad request instead of return 500 internal server error. This is a client request problem not service issue.