S allius/issue397 (#405)

* add Dashboards log handler to all known loggers

* add list of last 3 warnings/errors to page

* add note list to page

* create LogHandler for the dashboard

- simple memory log handler which stores the last
  64 warnings/errors for the dashboard

* render warnings/errors as note list

* add page for warnings and errors

* fix double defined build target

* add well done message if no errors in the logs

* translate page titles

* more translations

* add Notes page and table for important messages

* add unit tests

app/src/web/templates/page_notes.html.j2

@@ -0,0 +1,10 @@
+{% extends 'base.html.j2' %}
+
+{% block title %}{{_("TSUN Proxy - Important Messages")}}{% endblock title %}
+{% block menu3_class %}w3-blue{% endblock %}
+{% block headline %}<i class="fa fa-exclamation-triangle fa-fw"></i>  {{_('Important Messages')}}{% endblock headline %}
+{% block content %}
+  <div id="notes-list"></div>
+{% endblock content%}
+
+{% block footer %}{% endblock footer %}