- Added missing ErrorException initializer when creating RestRequest<T> from regular request.
- Modified Deserialize<T> so that the deserialization is only preformed when the request returned successfully. This because the current implementation threw an useless error when for example the request timed out and no correct header was present to be processed. This error was not cought and even if it was it would override the source error already stored in the request object.

In addition to this, a bare object was returned even when there was nothing to deserialize (invalid request, ex. 404). The returned object should of been null.
Better support for nullable types
Better support for nullable types
Improved handeling on nullable types (propper commit this time)

VS seems to be out of sync an doing strange things hence the odd commits
Added unit test for deserializer change
Fix up indentation
Added additional HTTP Status codes as valid responses
Changed indentation to tabs
Missed one indent...
Merge pull request #376 from Naliath/master

Preventing System.NullReferenceException when deserializing invalid responses