Remove default client approach from Resty, make resty further simple to use

[jeevatkm]

The goal of the issue is to bring a simpler approach and easy to use Resty. On v2 resty default client will be removed.

This is born from - On Gitter @moorereason approached with an article for Resty improvement. I have read and thought about it. When I look back. Initially, took an approach of DefaultClient similar to Go Http Client besides that no other reason.

I believe it's better to create an instance of Resty client with appropriate settings for usage.

[jeevatkm]

Also do cleanups, removal of the deprecated method and organize code 😄

[jeevatkm]

It's done 😄