This class defines out the semantics of what a 'Request' object looks like
when returned from a fetch() method. In general, a request object is
nothing more than the original keywordArgs from fetch with an abort function
attached to it to allow users to abort a particular request if they so choose.
No other functions are required on a general Request object return. That does not
inhibit other store implementations from adding extentions to it, of course.
This is an abstract API that data provider implementations conform to.
This file defines methods signatures and intentionally leaves all the
methods unimplemented.
For more details on fetch, see dojo.data.api.Read.fetch().