**What?**
- Deprecate all `DefaultClientConfigImpl` static defaults in favor of `CommonClientConfigKey` contain the default values
- Deprecate `IClientConfig#[setProperty, withProperty, containsProperty, setProperty, getPropertyAsInteger, getPropertyAsString, getPropertyAsBoolean]` all of which are replaced by `get` and `set`.
- Eliminate the awkward pattern of excessive conversion to and parsing of config string
- Leverage Java8 Optional to simplify config loading code

**Why?**
This is part of a long needed cleanup to simplify configuration loading

Changed IClientConfig interface. Move ClientConfigBuilder to be an inner class of IClientConfig. Added example of load balancing using URLConnection.

- Clean up unnecessary APIs in RetryHandler.
- Make sure follow redirect option is set correctly to NettyHttpClient
- General clean up and organizing.

- Created ribbon-http and ribbon-loadbalancer
- Removed httpasyncclient
- Refactor load balancer logic to make it based on Rx and decouple from Client APIs