isolate representation from content in GET request

Container server representation of data (received from backend) is isolated
into `create_listing()` call. GET() method will call `create_listing()`
when it's ready to create a serialized object listing. It will allow us to
customize that representation: get different listing, if backend supports
more interesting queries, for example.

Change-Id: I4fa03357d3d9e697bc3e1fb5da42d7572c6ae9b3
Fixes typo in man page

There is a simple typo in the man page of proxy-server.conf,
"client_timeout" is written as "client_timeoutt".
This commit fixes it.

Closes-Bug: #1326237
Change-Id: I98777f523906e4ed625de8f20a96979ea627aa1f
Merge "isolate representation from content in GET request"
Merge "Fixes typo in man page"