Sanic-security

+ Token exception revision.
+ Role assignment revision.
+ Docs revisions.

+ Initial admin account creation hotfix.

+ Verification hotfix.
+ Exception `json_response` changed to `json`.
+ Initial admin account username conforms to registration regex.
+ Test revision.
+ Docs revisions.

+ Session encode/decode revisions.
+ Documentation revisions.

+ Added `requires_second_factor` field to `AuthenticationSession` model.
+ Added optional `require_second_factor` parameter to `login()` .
+ `fulfill_second_factor()` method implemented.
+ Model `json()` method is now a property.
+ Exception message and code revisions.
+ Extensive documentation revisions.

+ Session `get_related()` helper function.
+ Test client & server revisions.
+ Account `disable()` helper function hotfix.