Split read and sync operations into separate classes
Split write operations into separate classes
Turn FeverAPI into a module

* Rename FeverAPI class to FeverAPI::Endpoint.
* Move Fever::Response to FeverAPI::Response under app/fever_api/
Split all operations into separate files
Add tests for read operations
Add tests for sync and write operations
Default params to empty hash
Merge pull request #268 from Koronen/refactor-fever-response

Refactor Fever::Response