Attached patch has the following changes:

1) AuthorizationMatrixProperty.java: add PermissionGroup for Run.class in the
DescriptorImpl.getAllGroups() result. This allows granting permission to delete
builds (issue #2532) and update build descriptions in the project config screen.

2) summary.jelly and AbstractBuild/index.jelly: set the object context for the
hasPermission check so it checks project-based permissions rather than using
Hudson.getInstance() context. This fixes whether or not the Workspace link is
shown in the project screen (summary.jelly) and whether or not Delete button and
add/update description are shown on a build screen (index.jelly).

3) I updated Functions.hasPermission with the same "degrade gracefully" code
that the checkPermission function has. Seems useful here too, though I don't
think this change is required for above change #2 to work (I think these always
pass a AccessControlled object, so don't use the extra code).