RingMainWindow : add account selector

- a new combo box is added to ringmainwindow, allowing to select an
account. It's required for the management of the upcoming contact
request implementation.

- Discretize informations shown on the the welcome page by account
protocols.

- Close views when the user swap between accounts.

Change-Id: I8b3f2ca75f8c532fcef0505d920bc662c096b705
Reviewed-by: Stepan Salenikovich <stepan.salenikovich@savoirfairelinux.com>
4 files changed