[NODEJS-1598] PoC of acs-node-sdk Rework

## Ticket Information
***JIRA Ticket***
https://jira.appcelerator.org/browse/NODEJS-1598

***Description***
This PR is about to raise a PoC of ACS Node SDK rework. It re-designs framework of acs-node-sdk, and supports multiple instances. It also provides a way to list all available ACS objects and methods including doc url for a good reference. Test framework with travis-ci is added too for a good and automatic test.

Since this is only a PoC, I only implemented ACS object "Users". If this way is towards to a good direction and passes code review, we will add all other ACS objects later.

## Get started
Please refer to readme file https://github.com/realpaul/acs-node-sdk/blob/NODEJS-1598_ReworkPoC/README.md for a general usage.
I actually prefer this style since I think it's more readable.

However, I generally want this to be a Class.

It would be better to re-write this as as Class constructor so that I can instantiate the library.

Here's what I want to be able to do (so we don't re-introduce the flaws in the current design):

(From dev code):

```javascript
var ACS = require('acs-node');

var acs = new ACS( {apikey:"123"} );
acs.Users.create({}, callback);
```

To implement this on the module side, you would need to make sure you're creating Classes.

```javascript
function ACS(config) {
    this.config = config;
}
ACS.prototype.amethod = function() {
};
module.exports = ACS;
```
And then you can internally hide all the instance level information in the ACS instance that is constructed (by new) such that I can have 10 different ACS sessions with different keys and session_ids etc and they can all run peacefully in the name Node VM.