Move to OkHttp instead of UrlConnection about http-request

[kevinsawicki]

Thanks for the suggestion but I don't want to add any dependencies.

The goal of this project is to be a single stand-alone class with no dependencies outside of the standard Java SDK classes.

[JakeWharton]

The way that we've done it was to have an optional dependency, detect it with a Class.forName lookup, and automatically use it if available. Takes about 15-20 lines of code.

This was it works out of the box with normal UrlConnection but if OkHttp happens to be on your classpath it will use it.

I'll send a pull and you can let me know what you think. We've done this on two other projects to great success.

[kevinsawicki]

Okay, sounds good.

[rossimo]

Very interested in this!