fix : various minor bugs.

- Forces to hide chat panel on video page when the user summon the video
  page

- Uses RingId instead of the name (wich is not necessarily unique) to make
  ContactsViewModel identfy a contact.

- Checks if contact reference is valid before getting the smart panel item.

- pass call list from daemon to the client trough an async function.

- sets visible the call button only if no call is on going.

- changes the avatar size to get some space for the call button.

Change-Id: Id3a0d03026503bdc5d1e844d8d4be8983da572d3
Tuleap: #790