[finished] Make the *restart now* checkbox more visible.

- Issue asks to make the setting more visible, which seems sensible to
   me. It **is** kind of hidden away for those distro's that make
   the setting visible (not everyone does).
 - While here, add a tooltip explaining what it does.

FIXES #893

src/modules/finished/FinishedPage.ui

@@ -61,6 +61,9 @@
      <property name="orientation">
       <enum>Qt::Vertical</enum>
      </property>
+     <property name="sizeType">
+      <enum>QSizePolicy::Fixed</enum>
+     </property>
      <property name="sizeHint" stdset="0">
       <size>
        <width>20</width>
@@ -72,14 +75,47 @@
    <item>
     <layout class="QVBoxLayout" name="verticalLayout_2">
      <item>
-      <widget class="QCheckBox" name="restartCheckBox">
-       <property name="text">
-        <string>&amp;Restart now</string>
-       </property>
-       <property name="checked">
-        <bool>false</bool>
-       </property>
-      </widget>
+      <layout class="QHBoxLayout" name="horizontalLayout">
+       <item>
+        <spacer name="horizontalSpacer">
+         <property name="orientation">
+          <enum>Qt::Horizontal</enum>
+         </property>
+         <property name="sizeHint" stdset="0">
+          <size>
+           <width>40</width>
+           <height>20</height>
+          </size>
+         </property>
+        </spacer>
+       </item>
+       <item>
+        <widget class="QCheckBox" name="restartCheckBox">
+         <property name="toolTip">
+          <string>&lt;html&gt;&lt;head/&gt;&lt;body&gt;&lt;p&gt;When this box is checked, your system will restart immediately when you click on &lt;span style=&quot; font-style:italic;&quot;&gt;Done&lt;/span&gt; or close the installer.&lt;/p&gt;&lt;/body&gt;&lt;/html&gt;</string>
+         </property>
+         <property name="text">
+          <string>&amp;Restart now</string>
+         </property>
+         <property name="checked">
+          <bool>false</bool>
+         </property>
+        </widget>
+       </item>
+       <item>
+        <spacer name="horizontalSpacer_2">
+         <property name="orientation">
+          <enum>Qt::Horizontal</enum>
+         </property>
+         <property name="sizeHint" stdset="0">
+          <size>
+           <width>40</width>
+           <height>20</height>
+          </size>
+         </property>
+        </spacer>
+       </item>
+      </layout>
      </item>
     </layout>
    </item>
@@ -89,7 +125,7 @@
       <enum>Qt::Vertical</enum>
      </property>
      <property name="sizeType">
-      <enum>QSizePolicy::Fixed</enum>
+      <enum>QSizePolicy::Expanding</enum>
      </property>
      <property name="sizeHint" stdset="0">
       <size>