Section 9.1.3: Describe call choreography for 202 Accepted (Async responses)

Follow Martin's presentation " [Choreography for Asynchrones Requests] ( https://www.oasis-open.org/committees/download.php/48081/AsyncODataProposal.ppt )" in the January F2F Accepted: https://www.oasis-open.org/committees/download.php/48097/odata-meeting-23_on-20130130_31-F2F-minutes.html#odata-31

I applied the proposal to the spec as described in the presentation with one deviation: In the presentation the async response was enclosed in an HTTP response with content -type message/http, I changed that to the content-type application/http with content-Transfer-Encoding binary for two reasons: 1. For message/http exists restrictions regarding line length and encodings. 2. Consistency with the OData batch format. In batch we use for the exactly same purpose (enclosing a singe HTTP response in a HTTP envelope) the content-typeheader with value application/http and a Content-Transfer-Encoding header with value binary. https://www.oasis-open.org/committees/download.php/48604/odata-core-v4.0-wd01-part1-protocol-2013-03-20.doc Accepted: https://www.oasis-open.org/committees/download.php/49026/odata-meeting-34_on-20130425_26-F2F-minutes.html#odata-31