rgw: move RGWRadosCtx into RGWRados

Signed-off-by: Yehuda Sadeh <yehuda@redhat.com>
rgw: s/RGWRadosCtx/ObjectCtx

Signed-off-by: Yehuda Sadeh <yehuda@redhat.com>
rgw: start reorganizing RGWRados

Need to reduce the various states of the different operations. The aim
is to separate the system objects operations from the data objects
operations, and compartmentalize the various systems.

Signed-off-by: Yehuda Sadeh <yehuda@redhat.com>
rgw: remove plain object processor

Signed-off-by: Yehuda Sadeh <yehuda@redhat.com>
rgw: pass around object context refrences, remove unused code

We want to make it clear that the object context is required for
non-system objects, pass it by reference (rather than by pointer). Make
the put processors get it as a constructor param and keep it on the
object.
Still haven't updated everything, as some stuff is going to change
anyway.
Remove the plain put processor, as it is not used anymore.

Signed-off-by: Yehuda Sadeh <yehuda@redhat.com>