Constructs an object that reflects the structure of an Okta Credentials Object
If you don't want to set a pw or recovery question just pass in null or empty string
@method constructCredentials
@param password
@param question
@param answer
@returns {{}}
function constructCredentials(password, question, answer) {
    var credentials = {};
    if(password) credentials.password = constructPassword(password);
    if(question && answer) credentials.recovery_question = constructRecoveryQuestion(question, answer);
    return credentials;
}