Update class.activitymodel.php

Fixed NotifyWallPost which does not store Format, RegardingUserID and Story into table Activity when inserting second line for wallpost-activity
Switch some direct access to GetValue() in ProfileController->_SetBreadcumbs().
- Added Gdn_Model->ExpandAttributes().
- Added Gdn_Model->CollapseAttributes().
- Relax check against the primary key for insert vs update.
- Filter out a few common post attributes in Gdn_Model->FilterForm().
Added Gdn_DataSet->ExpandAttributes().
Conversations:
- Always output a conversation subject if its there.
Fixes issue #1652.
Merge branch 'master' of github.com:vanillaforums/Garden
Fixes issue #1287.
If we are in debug mode then throw utility/update exceptions.
Merge branch 'patch-6' of https://github.com/R-J/Garden into R-J-patch-6
Merge branch 'master' of github.com:vanillaforums/Garden