Add capability passresolve and associated interface to handle it.

At present, the resolve capability is a receive-only capability . A user with a role having this capability can be assigned as resolver but can only pass it back to the administrator. In larger teams, it may be useful to allow resolvers to pass an issue from one to another directly. For example, one person handles adding new users, another doing teacher assignments. When a request comes, admin can pass it on to the first, and when that person is done, he/she could pass it to the second person directly.