Adding http logging capabilities

[paveliva]

Hi,

During our project we have faced with an issue that there is no chance to log request/response info. It is necessary for us to prevent and investigate possible issues in the future. And also we think that it can be quite useful for the library.

Please approve our merge request.

Thanks

[pblesi]

Hi @paveliva Thank you for your code submission. We think these changes are valuable and worth pursuing.

We ask that you make a few changes to your implementation

• Please leverage Java's built-in Logger class. We aim to be compatible with Java 6, so please do not use any features that are not present in Java 6.
• We attempt to keep our Libraries as idiomatic as possible across different languages. We already have an implementation for logging in our Ruby client library. Please follow the implementation in configuration.rb and http.rb as closely as possible.

Thanks!

[omgrr]

Looks like these changes are being addressed in a newly opened pull request. I'm going to close this one and track future efforts on that PR. Be sure to comment there if you have any concerns.