Avoid the use of single request to load files store and to create, rename, delete files

KFP-352 is divided into multiple tickets to better handle reviewing

In this ticket the following is done:

• Create separate reader, writer, and proxy if requires.

In files plugin right now we use container.getRequest().singleRequest( to send a request to the server. We should generalize architecture to send a request. Code will be easy to maintain, we will improve performance and we will reduce/reuse the code

Affected files

• Zarafa.plugins.files.data.ResponseHandler
• All the place where container.getRequest().singleRequest is used in files