Begin Implementing v3 starting with Cart and Catalog/Brands (v2 and v3) and more.. with Backward Compatible

[naveenrajbu]

Since this API was abandoned, I've started implementing my own Library using version 'v3' with Backward Compatible and can be easily edited for future releases.

As of now, this API will support all functions of Cart and also I've implemented Catalog APIs Starting with brands and will continue the same for other APIs.

Now you can use Cart (v3) and Brands (v2 and v3). checkout the extended documentation for how to use these methods

Feel free to create issues, Pull and Merge code.

Tickets #248 , #261