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/ui/Base.lproj/Broker.strings b/ui/Base.lproj/Broker.strings
new file mode 100644
index 0000000..1822dc7
--- /dev/null
+++ b/ui/Base.lproj/Broker.strings
@@ -0,0 +1,12 @@
+
+/* Class = "NSTextFieldCell"; title = "Display Role"; ObjectID = "1Rl-Yq-z7r"; */
+"1Rl-Yq-z7r.title" = "Display Role";
+
+/* Class = "NSTextFieldCell"; title = "Text Cell"; ObjectID = "3lU-Go-v0h"; */
+"3lU-Go-v0h.title" = "Text Cell";
+
+/* Class = "NSSearchFieldCell"; placeholderString = "Search or enter number"; ObjectID = "5vh-ub-Dsq"; */
+"5vh-ub-Dsq.placeholderString" = "Search or enter number";
+
+/* Class = "NSTextFieldCell"; title = "details"; ObjectID = "sQW-4V-hwv"; */
+"sQW-4V-hwv.title" = "details";