added control sidebar #10 (#87)

- added configurable sidebar #10
- added language switch in sidebar preferences tab #10
- added sidebar tab with kimai beta-info message #10
- use trait for repositories
- improved README

templates/bundles/AvanzuAdminThemeBundle/Partials/_control-sidebar.html.twig

@@ -0,0 +1,23 @@
+<aside class="control-sidebar control-sidebar-dark">
+    <ul class="nav nav-tabs nav-justified control-sidebar-tabs">
+        {% if kimai_context.control_sidebar is defined %}
+            {% for name, tab in kimai_context.control_sidebar %}
+                <li{% if loop.first %} class="active"{% endif %}><a href="#control-sidebar-{{ name }}-tab" data-toggle="tab"><i class="fa fa-{{ tab.icon }}"></i></a></li>
+            {% endfor %}
+        {% endif %}
+    </ul>
+    <div class="tab-content">
+        {% if kimai_context.control_sidebar is defined %}
+            {% for name, tab in kimai_context.control_sidebar %}
+                <div class="tab-pane {% if loop.first %}active{% endif %}" id="control-sidebar-{{ name }}-tab">
+                    {% if tab.controller is defined %}
+                        {{ render(controller(tab.controller)) }}
+                    {% elseif tab.template is defined %}
+                        {% include tab.template %}
+                    {% endif %}
+                </div>
+            {% endfor %}
+        {% endif %}
+    </div>
+</aside>
+<div class="control-sidebar-bg"></div>