function DiscogsOAuth(auth){
	this.config = util.merge({}, defaultConfig);
	this.auth = {method: 'oauth', level: 0};
	if(auth && (typeof auth === 'object') && (auth.method === 'oauth')){
		util.merge(this.auth, auth);
	}
}
Object constructor
@param {object} [auth] - Authentication object
@returns {DiscogsOAuth}