Remove unused pecan.request.context[]

Most of the controllers use pecan.request.context[] to keep
object IDs. There are several patches under review which propose
different context classes. As there were no agreement to use pecan
context and there are no explicit usage of this information in the
code I suggest to remove pecan.request.context[] part and use
correct version of context when we decide what should be used.

Change-Id: I83bcaa5e233ca488d8379b5db8b2f9272c6990e0
Merge "Remove unused pecan.request.context[]"