im: add a copy button to cm combobox

Change-Id: Id5b023beef399403d92056bc83a21db0df7a3838
Tuleap: #321
diff --git a/callwidget.h b/callwidget.h
index 84e3469..bfce156 100644
--- a/callwidget.h
+++ b/callwidget.h
@@ -79,6 +79,7 @@
     void on_contactMethodComboBox_currentIndexChanged(const QString& number);
     void on_ringContactLineEdit_textChanged(const QString& text);
     void on_imBackButton_clicked();
+    void on_copyCMButton_clicked();
 
 private slots:
     void callIncoming(Call* call);