code: function(opts){
    //defaults
    opts = opts || {};
    this.username           = opts.username    || '';
    this.password           = opts.password    || '';
    // oAuth Token
    this.accessToken        = opts.accessToken || '';
    // API Rate Limit Details
    this.rateLimit          = 5000;
    this.rateLimitRemaining = this.rateLimit;  //rateLimitRemaining starts as rateLimit
  }
docs: Sets credentials for GitHub access.
  @class Github3
  @constructor
  @param {Object} opts
  {String} .username GitHub username
  {String} .password GitHub password
  {Token } .accessToken GitHub oAuth Token