Implement Retrofit to connect to the API to fetch and publish data

[fed]

Try to replace the yambaclientlib.jar library with Retrofit.

Retrofit is a library that will let you define your API in a simple Java interface and will automagically convert it into a full-blown REST client.

More info on Retrofit here:

• http://square.github.io/retrofit/
• https://github.com/square/retrofit

And here're some guidelines to make a smart use of the library:

• http://blog.robinchutaux.com/blog/a-smart-way-to-use-retrofit/

[fed]

Here's the link to the source code of the current library: https://github.com/learning-android/yambaclientlib

And this is the web service's UI: http://yamba.marakana.com/