Add ability for admin to add user's identity to the registry.

[dchernokur]

Right now by default user can't add its own identity to the token registry, unless granted "Agent" role by the token deployer.
Currently the flow looks like this:

• user N1 creates identity
• admin user N2 grants Agent role to the user N1
• user N1 adds identity to the registry

I suggest to simplify the flow by adding ability for the admins to add user's identities to the registry from admin area.

• user N1 creates identity
• admin user N2 adds the identity from step 1 to the registry

Please check if adding by admin is possible at all, as well as find the way to see the list of "users identities", their status (added / not added to registry) and make a quick add button. Listening to the event of creating the identity may help to collect the list.

At this moment "Manage Identities" page revolves only around already added to the registry identities, but we want to make process of adding existing ones to the registry a bit simpler by admins.