By default, the OAuth2Authenticator escapes the scope parameter. When multiple scopes are provided (example: "basic+comments+relationships+likes"), some OAuth2 providers (such as Instagram) return an HTTP 400 BAD REQUEST on authentication. This is because the encoding of the "+" character is not accepted by some OAuth2 providers (such as Instagram). This commit adds a property named DoNotEscapeScope that can be set to true to circumvent the issue.