Added Remove Connection and Updated Email Invite

Connections can now be removed using /network. I copied the UI/UX for
deleting from removing books, so it gives you an undo prompt (called
reconnect--still requires confirmation). I realized though, that we
should probably do a Confirm/Cancel button instead.

I updated the Invite by Email to be Invite by Gmail. Clicking "Send with
Gmail" opens up a Gmail Compose window with the To, Subject, and Body
filled out. I couldn't figure out how to use hyperlinks, though.