Update RibbonModule.java

I noticed several severe issues with the use of feign client and feign.RibbonModule. All this while I was under the impression that it leverages the Ribbon implementation of http client(RestClient) but it does not. 

I saw the following issues:
1. Connection leaks. The server runs out of file descriptors after a day of hundreds of client calls.
2. Every time a request is made, a new connection is opened.
3. Also some of the Ribbon properties like shiro-client.ribbon.OkToRetryOnAllOperations=false are ignored.