chat: update RecentModel selection

Clear RecentModel current index:
- during a call when the call is OVER
- in chat view when clicking on back button

This allow to reselect the previous row, and visually reset
the row (remove highlight state)

Change-Id: I36f531c6304ce48f0be3cc541f28a21d73a05262
Tuleap: #202
diff --git a/src/SmartViewVC.mm b/src/SmartViewVC.mm
index d026458..405148f 100644
--- a/src/SmartViewVC.mm
+++ b/src/SmartViewVC.mm
@@ -98,8 +98,10 @@
     QObject::connect(RecentModel::instance().selectionModel(),
                      &QItemSelectionModel::currentChanged,
                      [=](const QModelIndex &current, const QModelIndex &previous) {
-                         if(!current.isValid())
+                         if(!current.isValid()) {
+                             [smartView deselectAll:nil];
                              return;
+                         }
 
                          auto proxyIdx = RecentModel::instance().peopleProxy()->mapFromSource(current);
                          if (proxyIdx.isValid()) {