List count of untranslated strings in notification mail

Signed-off-by: Michal Čihař <michal@cihar.com>

weblate/html/mail/footer.html

@@ -10,7 +10,7 @@
 <td>{% trans "Translated strings:" %}</th><td>{{ translation.translated }} ({{ translation.get_translated_percent }}%)</td>
 </tr>
 <tr>
-<td>{% trans "Untranslated strings:" %}</th><td>{{ translation.translated }} ({{ translation.get_untranslated_percent }}%)</td>
+<td>{% trans "Untranslated strings:" %}</th><td>{{ translation.untranslated }} ({{ translation.get_untranslated_percent }}%)</td>
 </tr>
 <tr>
 <td>{% trans "Fuzzy strings:" %}</th><td>{{ translation.fuzzy }} ({{ translation.get_fuzzy_percent }}%)</td>

weblate/html/mail/footer.txt

@@ -2,6 +2,7 @@
 
 {% trans "Total strings:" %} {{ translation.total }}
 {% trans "Translated strings:" %} {{ translation.translated }} ({{ translation.get_translated_percent }}%)
+{% trans "Untranslated strings:" %} {{ translation.untranslated }} ({{ translation.get_untranslated_percent }}%)
 {% trans "Fuzzy strings:" %} {{ translation.fuzzy }} ({{ translation.get_fuzzy_percent }}%)
 
 {% blocktrans %}You can translate at {{ translation_url }}{% endblocktrans %}