When trying to go online/offline we're always waiting for confirmation
from the stack (even if it's a timeout) so the delayed pattern is a good choice.
Introduce a state-changed signal which also gives a reason for why the state
changed. This will allow the UI to give some meaningful feedback to the user.
Additionally we can get rid of a number of things that were not really states,
but rather reasons for why a state changed (f.e. authentication failures).
CallsAccountOverview allows user to view, add and edit VoIP accounts
(currently SIP only).
Each CallsAccount is represented by a CallsAccountRow.
account-row: Staying alive
