Cleaned up ChefApi and ChefService interfaces

This pull request just renames a few methods in the ChefApi to follow a consistent naming convention, and reorders them so all methods are properly grouped. There are no changes to the code just the bits to follow the more convenient naming convention.

Also cleaned up the ChefService and improved the javadoc on the methods of both interfaces.

@noorul, could you take this PR into account when adding new features to the API?