Resource Manager PV plugin

Checkpoint on PV, resource, selection, and operation refactor.

• Implement some stubbed methods in smtk::operation classes and test them.
• Add C++11 callbacks for listening to operator events (all of them, not just individual operators like the model- operator callbacks did).
• Add behaviors to the ParaView extensions that do client- server communication of selections.
• Add pqSMTKResourceManager proxy that gets created by pqSMTKResourceManagerBehavior upon plugin startup. All the selection management stuff in the behavior should eventually be moved into the proxy class.
• Add pqSMTKResource proxy that registers itself with the VTK/PV-wrapping of SMTK's resource manager.
• Fix documentation and add stubs for documenting the smtk/extension directory.
• Add Qt extension classes that expose the new descriptive phrase classes in smtk/view.
• Use the new qtDescriptivePhraseModel in a panel to show resources in ParaView as a behavior.
• Eliminate client-server duality. For now, we work only with PV's built-in server, not separate client+server processes. This means that there is no need for operator forwarding, separate resources on the client and server, problems synchronizing the client-only attribute panels with models that are modified only on the server, etc.