Implement Augmented Backus-Naur Form (ABNF) Syntax checks

[bgaillard]

The ResponseParser component and the ErrorResponse, CriticalErrorResponse and SuccessfulResponse implements several checks to ensure an OAuth 2.0 returns responses which are compliant with the OAuth 2.0 specifications.

However several Agmented Backus-Naur Form checks could be implemented additionnaly to ensure that each property of the JSON responses are valid.

An AbnfUtils component has been created with skeleton methods, we should implement all those methods and unit test them to be compliant with https://tools.ietf.org/html/rfc6749#appendix-A.