Impersonation in GateIn

It would be nice to have impersonation feature available in GateIn. This will allow administrator to temporarily gain identity of another user, perform some actions in GateIn UI on behalf of this user and verify that everything looks as expected (for example protected pages, which should not be seen by particular user are really not seen etc.)

Some prototype is available on github:
https://github.com/mposolda/gatein-impersonation
https://github.com/ozoli/gatein-impersonation
but will require proper specification, review, and more work.

Also for UI, it would be better to have the functionality available directly in orgManagementPortlet. I though about possibility to have another action for "impersonate" in UserManagement. So having 3 actions like "Edit", "Delete", "Impersonate". I. this case, we will also need new icon in UI etc...