Add tooltips for accessibility

Most of the UI was lacking tooltips for accessibility.
This patch is a roundup of all the fields, buttons, and selectors,
for setting up a first stone to build upon.

Change-Id: I63f5e9aa1c5e96c61fd04540df50895579bb293d
Reviewed-by: Anthony Léonard <anthony.leonard@savoirfairelinux.com>
diff --git a/deleteaccountdialog.ui b/deleteaccountdialog.ui
index 02e275d..c30cdaa 100644
--- a/deleteaccountdialog.ui
+++ b/deleteaccountdialog.ui
@@ -134,6 +134,9 @@
          <height>30</height>
         </size>
        </property>
+       <property name="toolTip">
+        <string>Cancel contact deletion button</string>
+       </property>
        <property name="text">
         <string>Cancel</string>
        </property>
@@ -160,6 +163,9 @@
          <height>30</height>
         </size>
        </property>
+       <property name="toolTip">
+        <string>Validate contact deletion button</string>
+       </property>
        <property name="text">
         <string>Ok</string>
        </property>