conference: first implementation

This commit adds conferences management

- create conference by joining two ongoing calls/conferences
- create conference by calling a new peer and joining him to the ongoing
call/conference
- hanging up conferences

This commit relies on CallModel and RecenModel selection models
interactions to update call view and Smartlist row selected.

Change-Id: Ib9f6b9b870e66c8ccfb5115ad6fdb592c625eb58
Tuleap: #114
diff --git a/CMakeLists.txt b/CMakeLists.txt
index a8d14c1..0693423 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -188,6 +188,8 @@
 ${CMAKE_CURRENT_SOURCE_DIR}/data/dark/ic_call_missed.png
 ${CMAKE_CURRENT_SOURCE_DIR}/data/dark/ic_call_made.png
 ${CMAKE_CURRENT_SOURCE_DIR}/data/dark/ic_action_transfer.png
+${CMAKE_CURRENT_SOURCE_DIR}/data/dark/ic_action_add_participant.png
+${CMAKE_CURRENT_SOURCE_DIR}/data/dark/ic_action_merge_calls.png
 ${CMAKE_CURRENT_SOURCE_DIR}/data/dark/ancrage.png
 ${CMAKE_CURRENT_SOURCE_DIR}/data/dark/audio.png
 ${CMAKE_CURRENT_SOURCE_DIR}/data/dark/ic_person_add.png